Electrical and Electronics Engineering publications abstract of: 05-2017 sorted by title, page: 13

» On the Optimal Set of Channels to Sense in Cognitive Radio Networks
Abstract:
In the channel selection problem, a secondary user (SU) senses a subset of size out of existing channels, and then accesses up to sensed-free channels. Given , , , and some estimates on the rates of channels, and the sensing accuracy, the channel selection problem asks what set of channels SU should sense to maximize its throughput. The intuitive answer is the set of channels with the highest rewards, where the reward of a channel is defined as the expected number of bits that can be successfully transmitted on that channel. Surprisingly, the above-mentioned intuitive solution is not optimal when . In this letter, we study the case , and propose polynomial-time optimal solutions for special cases where or where or are small. We also derive an upper bound on the maximum achievable throughput, and propose a generic near-optimal heuristic algorithm.
Autors: Afshin Arefi;Majid Khabbazian;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1103 - 1106
Publisher: IEEE
 
» On the Optimal Tone Spacing for Interference Mitigation in OFDM-IM Systems
Abstract:
Orthogonal frequency division multiplexing with index modulation (OFDM-IM) has been recently proposed as an efficient technique to improve the error performance and enhance the spectral efficiency achieved by the classical OFDM. In this letter, we minimize the presence of intercarrier and intersymbol interference, experienced by OFDM-IM systems under mobility conditions and multipath scenarios, by selecting the appropriate tone spacing between adjacent subcarriers. Finally, we prove that the optimal value of tone spacing increases the system capacity, occupying only the necessary amount of bandwidth, and provide closed-form expressions for the interference power per active subcarrier.
Autors: Georgia D. Ntouni;Vasileios M. Kapinas;George K. Karagiannidis;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1019 - 1022
Publisher: IEEE
 
» On the Optimization Model for Multi-Hop Information Transmission and Energy Transfer in TDMA-Based Wireless Sensor Networks
Abstract:
Wireless energy transfer (WET) has been considered a promising technique for prolonging the lifetime of wireless networks. In this letter, the joint optimization problem of multi-hop information transmission and energy transfer in TDMA-based multi-hop wireless sensor networks is modeled. Moreover, a more realistic energy consumption model is proposed, which takes the energy consumption of compression, communication, and wireless energy transfer into account. A nonlinear programming problem is formulated to achieve the maximal source rate utility. Finally, through the numerical results, the impact of system parameters on rate utility is investigated, and the role of WET in improving network performance is verified.
Autors: Weiqiang Xu;Weiwei Cheng;Yushu Zhang;Qingjiang Shi;Xiaodong Wang;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1095 - 1098
Publisher: IEEE
 
» On the Outage Probability of MIMO Full-Duplex Relaying: Impact of Antenna Correlation and Imperfect CSI
Abstract:
This paper analyzes the performance of multiple-input multiple-output (MIMO) full-duplex (FD) relaying systems, where the source and destination nodes are equipped with single antenna and communicate via a dual-hop amplify-and-forward (AF) relay with multiple receive and transmit antennas. The system performance due to practical wireless transmission impairments of spatial fading correlation and imperfect channel state information (CSI) is investigated. At the relay, the loopback self-interference (LI) is mitigated by using the receive zero-forcing (ZF) precoding scheme, then steering the signal to the destination by using a maximum and ratio transmission (MRT) technique. To this end, new exact closed-form expressions for the outage probability are derived, where the case of arbitrary, exponential, and no correlations are considered. Meanwhile, for better system performance insights, simpler outage probability lower bound expressions are also included, through which the achievable diversity order of the receive ZF/MRT scheme is shown to be , where and are the number of relay receive and transmit antennas, respectively. Numerical results sustained by Monte Carlo simulations show the exactness and tightness of the proposed closed-form exact and lower bound expressions, respectively. In addition, it is seen that the outage probability performance of FD relaying outperforms that of the conventional half-duplex (HD) relaying at low to medium signal-to-noise ratio (SNR). However, at high SNR, the performance of HD relaying outperforms that of the FD relaying. Furthermore, in the presence of channel estimation errors, an outage probability error floor is seen at high SNR. Therefore, for optimum outage performance, hybr- d relaying modes that switches between HD and FD relaying modes is proposed.
Autors: Ahmed Almradi;Khairi Ashour Hamdi;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 3957 - 3965
Publisher: IEEE
 
» On the Performance of HARQ-IR Over Nakagami-m Fading Channels in Mobile Ad Hoc Networks
Abstract:
In this paper, outage performance of hybrid automatic repeat request (HARQ) with incremental redundancy over Nakagami-m fading channels in a mobile ad hoc network is analyzed. Different from prior analyses, both interlink interference and random distribution of the nodes are considered, which makes the analysis practical and challenging. Based on an orthogonal polynomial approximation, the probability distribution of the product of multiple shifted signal-to-interference-and-noise ratios (SINRs) and the outage probability are derived in closed forms. The impacts of various system parameters including the intensity of source nodes, the number of retransmissions and the packet rate on the outage probability are then studied thoroughly. The closed-form outage probability enables further analysis of a wide range of performance metrics and delay limited throughput (DLT) is particularly discussed here. It is found that a limited number of retransmissions is sufficient to achieve the maximum DLT. With the analytical results, the optimal packet rate to maximize the DLT is also found. To characterize the performance of the whole network, network DLT (NDLT), which is the maximum achievable aggregated DLT in a unit area under a certain outage constraint, is finally introduced. The scaling law of NDLT over the network density is revealed. Specifically, the NDLT scales linearly with the network density when the network is sparse, while it follows the power law over the network density where is the path loss exponent when the network is dense.
Autors: Haichuan Ding;Zheng Shi;Shaodan Ma;Chengwen Xing;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 3913 - 3929
Publisher: IEEE
 
» On the Scaling Behavior of the Average Rate Performance of Large-Scale Distributed MIMO Systems
Abstract:
To support the massive data traffic in the near future, the distributed antenna system has become a promising candidate for the next-generation cellular system. Due to the lack of a closed-form expression, how the average rate performance scales with a large number of distributed base-station (BS) antennas is not well understood. This paper focuses on the average rate performance of the downlink channel of a large-scale distributed antenna system. By assuming that the number of BS antennas at each cluster and the number of user antennas go to infinity with , asymptotic lower-bounds of the average per-antenna capacities with and without channel state information at the transmitter side (CSIT) in the single-user case are characterized as an explicit function of the ratio and the number of BS antenna clusters . Simulation results verify that the average per-antenna capacities with and without CSIT logarithmically increase with in the orders of and , respectively, where is the path-loss factor. The analysis is further extended to the multiuser case with uniformly distributed users. By assuming that - inline-formula>$N,N_crightarrow infty$ with , an asymptotic lower-bound of the average per-antenna rate with block diagonalization (BD) is derived. Simulation results verify that the average per-antenna rate scales in the order of if the ratio is fixed. The effect of the cluster size on the average rate performance is further analyzed. Simulation results verify that for a given number of BS antennas, the average per-antenna capacities with and without CSIT in the single-user case and the average per-antenna rate with BD in the multiuser case increase monotonically as the number of BS antennas at each cluster decreases, which indicates that a fully distributed BS antenna layout can achieve the highest average rate performance.
Autors: Zhiyang Liu;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 4029 - 4043
Publisher: IEEE
 
» On the Secrecy Rate Maximization With Uncoordinated Cooperative Jamming by Single-Antenna Helpers
Abstract:
A practical uncoordinated cooperative jamming (UCJ) scheme is proposed in this paper to enhance the physical layer security of the single-input-single-output (SISO) wiretap channel. Differing from the existing works, all the helpers in this UCJ scheme are uncoordinated single-antenna uplink users, and each helper transmits a jamming signal independently to confound the eavesdropper. The intended receiver plays the role of base station in the cellular systems as well as a control center to properly allocate the jamming power of each helper to maximize the secrecy rate. Two cases are addressed in solving the secrecy rate maximization problem, namely, the global channel state information (CSI) case and the partial CSI case. The optimal solution is obtained in the global CSI case, and a near-optimal solution is obtained under the secrecy outage probability constraint in the partial CSI case. Numerical results show that the performance of the proposed scheme is comparable with the existing works.
Autors: Xiaoyan Hu;Pengcheng Mu;Bo Wang;Zongmian Li;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 4457 - 4462
Publisher: IEEE
 
» On the Simulation of Everything
Abstract:
Affordable computing and memory capacity have enabled fascinating work in the "world" of computer visualization and simulation. As high-resolution complexities are modeled, offering new and sometimes unexpected results, these intricate artifacts answer questions while leading to new ones.
Autors: Vinton G. Cerf;
Appeared in: IEEE Internet Computing
Publication date: May 2017, volume: 21, issue:3, pages: 103 - 104
Publisher: IEEE
 
» On the Spectral Efficiency of Selective Decode-and-Forward Relaying
Abstract:
Multirelay cooperative relaying enables spatial diversity, often at the expense of spectral efficiency. To alleviate the loss in spectral efficiency due to half-duplex relaying and transmission over orthogonal channels, we propose a novel transmission scheme for selective decode-and-forward (DF) networks. In this scheme, we assume that destination may receive signals from transmitting nodes with different modulation levels. Particularly, we obtain a closed-form expression for both end-to-end (E2E) average error probability and spectral efficiency in such a scheme. Subsequently, using these closed-form expressions and average channel statistics, we perform joint optimization of power allocation and modulation level selection to maximize the E2E spectral efficiency while maintaining a target E2E average error probability and a set of transmit power constraints. Simulation results demonstrate that the transmission scheme proposed herein improves the E2E spectral efficiency significantly, in comparison with the conventional adaptive DF transmission scheme.
Autors: Hamza Umit Sokun;Halim Yanikomeroglu;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 4500 - 4506
Publisher: IEEE
 
» On the Statistics of Coherence Estimators for Textured Clutter Plus Noise
Abstract:
This letter presents a theoretical analysis of the impact of thermal noise on the statistics of the classical as well as a modified estimator for the cross-correlation coefficient between two receive channels, which follow a noisy compound clutter model. This correlation coefficient, in the synthetic aperture radar (SAR) context often called coherence, is widely used as an important quality parameter in the field of SAR interferometry, SAR change detection, and SAR ground moving target indication. Based on a novel closed-form expressions for the probability density function (pdf) for integer number of averaged samples (or looks), it is shown that, contrary to widespread belief, the clutter texture does not cancel out when the noise contribution is taken into account. It is further demonstrated that the new pdfs can be used to derive the bias and variance of the sample coherence in analytical closed form. Thereby, the impact of the texture on the estimators is analyzed.
Autors: Christoph H. Gierull;
Appeared in: IEEE Geoscience and Remote Sensing Letters
Publication date: May 2017, volume: 14, issue:5, pages: 679 - 683
Publisher: IEEE
 
» On the VLSI Energy Complexity of LDPC Decoder Circuits
Abstract:
Sequences of randomly generated bipartite configurations are analyzed; under mild conditions almost surely such configurations have minimum bisection width proportional to the number of vertices. This implies an almost sure scaling rule for the energy of directly-implemented low-density parity-check (LDPC) decoder circuits for codes of block length and maximum node degree . It also implies an lower bound for serialized LDPC decoders. It is also shown that all (as opposed to almost all) capacity-approaching, directly-implemented non-split-node LDPC decoding circuits, have energy, per iteration, that scales as , where is the reciprocal gap to capacity, is code rate, and is channel capacity.
Autors: Christopher G. Blake;Frank R. Kschischang;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2017, volume: 63, issue:5, pages: 2781 - 2795
Publisher: IEEE
 
» On Unified Numerical Algorithm for 3-D Scattering From Dielectric and PEC Random Rough Surfaces
Abstract:
We present a unified fast scattering algorithm for dielectric random rough surfaces that asymptotically reduces to the perfect electric conductor (PEC) case when the loss tangent grows extremely large. The Coifman wavelets are employed to implement Galerkin’s procedure in the method of moments (MoM). The Coiflets-based surface integral equations (IEs) consist of both the tangential and normal components of electromagnetic fields as unknowns. The inherited mathematical superiority, e.g., local multiresolution analysis and high regularity with Holder index 1.449 in smoothness, allows efficiently implementing both electric field IE and magnetic field IE. Due to the high-precision one-point quadrature, the Coiflets yield fast evaluations of the most off-diagonal entries, reducing the matrix fill effort from O(N2) to O(N). The orthogonality and Riesz basis of the Coiflets generate well-conditioned impedance matrix, with rapid convergence for the conjugate gradient solver. In addition, a semianalytical expression of the tapered-wave carried power is derived, which speeds up computations of the normalization factor of scattering coefficients. Numerical results demonstrate that the reduced PEC model does not suffer from ill-posed problems, namely, matrix condition numbers are kept small and solutions are stable under extremely large loss tangent, where normal components of -field and tangential -field have vanished. Compared with the previous publications and laboratory measurements, good agreement is observed.
Autors: Lisha Zhang;Guangwen George Pan;Jimmy A. Jones;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2017, volume: 65, issue:5, pages: 2615 - 2623
Publisher: IEEE
 
» On-Chip Investigation of Phase Noise in Monolithically Integrated Gain-Switched Lasers
Abstract:
Phase noise in gain-switched lasers is investigated theoretically using the semiconductor laser rate equations and compared with the experimental results from monolithically integrated devices. The phase noise of a gain-switched laser is modelled both with and without injection-locking using the rate equations for a single-mode laser. Phase noise is found to increase with gain-switching, and decrease when injection-locked to a master laser. This trend is then observed experimentally on-chip with monolithically integrated devices without the use of an isolator.
Autors: Justin K. Alexander;Padraic E. Morrissey;Ludovic Caro;Mohamad Dernaika;Niall P. Kelly;Frank H. Peters;
Appeared in: IEEE Photonics Technology Letters
Publication date: May 2017, volume: 29, issue:9, pages: 731 - 734
Publisher: IEEE
 
» Online Condition Monitoring for Both IGBT Module and DC-Link Capacitor of Power Converter Based on Short-Circuit Current Simultaneously
Abstract:
Insulated-gate bipolar transistor (IGBT) modules and dc-link capacitors are important parts in the majority of power electronic converters which contribute to cost, size, and failure rate on a considerable scale. This paper presents an online condition monitoring method for both IGBT modules and dc-link capacitors of power converters based on short-circuit current of an IGBT module, which is a good condition indicator according to the theory analysis. The failure prediction of dc-Link capacitor is realized by equivalent series resistance, which can be calculated by short-circuit current and a step voltage, and the bond wires fatigue can also be identified by the short-circuit current. The proposed method is capable for detecting small changes in the failure indicators of IGBT modules and electrolytic capacitors, and its effectiveness is validated by a confirmatory experiment. The novelty of the proposed method is that the degradations of IGBT modules and capacitors can be identified simultaneously, and has the merits of low cost and circuit simplicity
Autors: Pengju Sun;Can Gong;Xiong Du;Quanming Luo;Haibo Wang;Luowei Zhou;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: May 2017, volume: 64, issue:5, pages: 3662 - 3671
Publisher: IEEE
 
» Online Optimal Operation of Parallel Voltage-Source Inverters Using Partial Information
Abstract:
In this paper, a novel optimal learning algorithm for partially unknown voltage-source inverters (VSIs) operating in parallel is presented. The algorithm designs game-theory-based distributed controllers to provide the appropriate working voltage magnitude and frequency at the load by converting dc voltage to ac voltage at the parallel VSIs. It takes advantage of information from the neighboring low pass filters to improve harmonic distortion and guarantee equal sharing of the load current across the VSIs while avoiding current circulation during transient and ensuring stability and robustness. It builds upon the ideas of approximate dynamic programming (ADP) and uses only partial information of the system and the exosystem, which is connected only to some of the VSIs. The proposed framework was tested in simulations to show its effectiveness.
Autors: Kyriakos G. Vamvoudakis;João P. Hespanha;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: May 2017, volume: 64, issue:5, pages: 4296 - 4305
Publisher: IEEE
 
» Online Ski Rental for ON/OFF Scheduling of Energy Harvesting Base Stations
Abstract:
The co-existence of small cell base stations (SBSs) with conventional macrocell base station is a promising approach to boost the capacity and coverage of cellular networks. However, densifying the network with a viral deployment of SBSs can significantly increase energy consumption. To reduce the reliance on unsustainable energy sources, one can adopt self-powered SBSs that rely solely on energy harvesting. Due to the uncertainty of energy arrival and the finite capacity of energy storage systems, self-powered SBSs must smartly optimize their ON and OFF schedule. In this paper, the problem of ON/OFF scheduling of self-powered SBSs is studied, in the presence of energy harvesting uncertainty with the goal of minimizing the operational costs consisting of energy consumption and transmission delay of a network. For the original problem, we show that an algorithm can solve the problem in the illustrative case. Then, to reduce the complexity of the original problem, an approximation is proposed. To solve the approximated problem, a novel approach based on the ski rental framework, a powerful online optimization tool, is proposed. Using this approach, each SBS can effectively decide on its ON/OFF schedule autonomously, without any prior information on future energy arrivals. By using competitive analysis, a deterministic online algorithm and a randomized online algorithm (ROA) are developed. The ROA is then shown to achieve the optimal competitive ratio in the approximation problem. Simulation results show that, compared with a baseline approach, the ROA can yield performance gains reaching up to 15.6% in terms of reduced total energy consumption of SBSs and up to 20.6% in terms of per-SBS network delay reduction. The results also shed light on the fundamental aspects that impact the ON time of SBSs while demonstrating that the proposed ROA can reduce up to 69.9% the total cost compared with a bas- line approach.
Autors: Gilsoo Lee;Walid Saad;Mehdi Bennis;Abolfazl Mehbodniya;Fumiyuki Adachi;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: May 2017, volume: 16, issue:5, pages: 2976 - 2990
Publisher: IEEE
 
» Open-End Multilevel Six-Phase Machine Drive System With Five Three-Leg Converters
Abstract:
This paper proposes and investigates a multilevel ac six-phase motor drive. The system is composed of five isolated three-leg voltage source inverters feeding the open-end windings of an asymmetrical six-phase induction motor (SPIM), which is adequate to generate multilevel voltages for high-power systems with voltage rating restrictions. A simple space vector pulse-width modulation (PWM) based on three similar individual planes and its implementation by means of equivalent level-shifted PWM are presented. A space vector pattern with a high number of voltage vectors redundancies is obtained. These redundancies and the application sequence of the voltage vectors are selected to minimize the amount of changes in the switching states and to decrease the harmonic distortion of the generated voltages. The vector pattern of this optimal modulation is obtained by analyzing only one plane and applied in the same way to the three planes as if they were independent. The developed PWM techniques have low computational complexity and are suitable for low-cost hardware implementations. Simulation results are used to compare the proposed topology with a conventional configuration in terms of harmonic distortion and semiconductor losses. Experimental results demonstrate the feasibility of the proposed drive system.
Autors: Ayslan Caisson Norões Maia;Cursino Brandão Jacobina;Nayara Brandão de Freitas;Italo Roger Ferreira Moreno Pinheiro da Silva;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 2271 - 2281
Publisher: IEEE
 
» Open-End Nine-Phase Machine Conversion Systems
Abstract:
This paper proposes four open-end nine-phase conversion systems with a reduced number of controlled switches. For this to be achieved, a converter is shared among the three three-phase groups that compose the machine. In addition, in order to reduce the number of controlled switches even more, three of the studied topologies with a shared converter make use of diodes replacing some of the switches. Because of the shared converter, the configurations that make use of diodes are only applied for machines with no spatial shift between the machine three three-phase groups. Analysis of harmonic distortion for equal and unequal dc-link voltages is presented. It is shown that the harmonic distortion for configurations with diodes are higher when unequal dc-link voltages are used. Besides, study of machine torque ripple is performed and a pulse-width modulation strategy modification is made aiming torque ripple reduction for two of the proposed conversion systems. Simulation and experimental results are presented to validate the theoretical approach.
Autors: Victor Felipe Moura Bezerra Melo;Cursino Brandão Jacobina;Nayara Brandão de Freitas;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 2329 - 2341
Publisher: IEEE
 
» Open-Loop Coherent Distributed Arrays
Abstract:
The ability to cohere the wireless operations between separate, moving microwave systems enables significant increases in capability for remote sensing, radar, communications, and other microwave wireless applications. Open-loop coherent distributed arrays, which are distributed systems of nodes that coherently coordinate without external signal inputs from the destination, are introduced in this paper. A model of the signal received from a coherent distributed array is derived, and a statistical analysis of the variation in signal power in the presence of coordination errors is presented. Requirements on the tolerable errors for internode range measurement, beamsteering angle measurement, and internode clock phase synchronization are given as a function of the probability of achieving a given signal power. Approaches for achieving the necessary internode range and angle measurements are presented, and the experimental results of a novel one-way clock transfer approach to phase synchronization are shown. These examples demonstrate the feasibility of implementing coherent distributed arrays on moving platforms operating at frequencies extending into the microwave region.
Autors: Jeffrey A. Nanzer;Robert L. Schmid;Thomas M. Comberiate;Jason E. Hodkin;
Appeared in: IEEE Transactions on Microwave Theory and Techniques
Publication date: May 2017, volume: 65, issue:5, pages: 1662 - 1672
Publisher: IEEE
 
» Open-Loop Precoder Design for Spatial Multiplexing Systems in Transmit Correlated MIMO Channels
Abstract:
The performance of spatial multiplexing (SM) systems is significantly degraded in transmit correlated multiple-input multiple-output (MIMO) channels. In communication systems that are available for feedback, precoding can enhance performance by exploiting channel state information (CSI) at the transmitter. However, broadcasting systems have no reverse channel nor any CSI. Furthermore, channel mismatches in communication systems severely affect performance. For these systems, open-loop precoders that require no feedback CSI were proposed. However, an analytical precoder design method was not presented in the previous works. In this paper, we present an open-loop precoder design method for SM systems with a maximum-likelihood receiver in transmit correlated MIMO channels. We first describe how to design an open-loop precoder using a rotational matrix over the amplitude of the correlation. Our precoder design method is derived by observing the effect of correlation mismatch between the feedback CSI and the actual channel condition on a minimum Euclidean distance-based precoder. Next, we present a method to design an open-loop precoder that takes into account the impact of the phase of the correlation. For this precoder, a phase rotation matrix is added on the rotational matrix, and optimum parameters are obtained by maximizing the worst-case minimum distance for the phase of the correlation. The simulation results illustrate the validity of proposed open-loop precoder in transmit correlated MIMO channels.
Autors: Jungyup Jang;Dong Ho Kim;Ye Hoon Lee;Jong-Soo Seo;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 3843 - 3855
Publisher: IEEE
 
» Open-Type Magnetic Shields for Optical Fiber Coil Protection With Coaxial Foil Tubes
Abstract:
To decrease the considerable nonreciprocal phase drift caused by environmental magnetic fields in fiber-optic gyroscope (FOG), magnetic shields on optical fiber coil (OFC) are necessarily used in medium- and high-accuracy FOG protection. Cubic boxes and spherical shells without any gaps have been widely adopted for decades in shields, posing challenge for tradeoff between weight limitation of shields and its shielding demand yet. Here, an open-type magnetic shields (OMSs) with several coaxial permalloy foil tubes in few hundred micrometers thickness is proposed, overlaying on the winding process of fiber coil and finally combining with OFC as an integration module (OFC-OMS). The shielding effectiveness (SE) and longitudinal availability were adjustable by changing permalloy tubes’ thickness, intervals between coaxial foil tubes, and extended length in endcaps. The optimized result showed that an OMS set with six coaxial permalloy foil tubes achieved a longitudinal availability of 82.6% for SE above 20dB in both axial and radial magnetic field and further revealed anisotropic shielding effect in axial magnetic field remarkably resulting in a 40-dB longitudinal availability of 70.1%. Total mass of OMS reduced by around 75% comparing with the conventional magnetic shields for OFC, which showed immense potentials on reduction of FOG size and processing cost.
Autors: Haixia Liu;Kaiming Liu;Zhenjiang Liang;Xiaojun Ma;
Appeared in: IEEE Transactions on Magnetics
Publication date: May 2017, volume: 53, issue:5, pages: 1 - 7
Publisher: IEEE
 
» OpenCL-Based FPGA-Platform for Stencil Computation and Its Optimization Methodology
Abstract:
Stencil computation is widely used in scientific computations and many accelerators based on multicore CPUs and GPUs have been proposed. Stencil computation has a small operational intensity so that a large external memory bandwidth is usually required for high performance. FPGAs have the potential to solve this problem by utilizing large internal memory efficiently. However, a very large design, testing and debugging time is required to implement an FPGA architecture successfully. To solve this problem, we propose an FPGA-platform using C-like programming language called open computing language (OpenCL). We also propose an optimization methodology to find the optimal architecture for a given application using the proposed FPFA-platform. According to the experimental results, we achieved 119 237 Gflop/s of processing power and higher processing speed compared to conventional GPU and multicore CPU implementations.
Autors: Hasitha Muthumala Waidyasooriya;Yasuhiro Takei;Shunsuke Tatsumi;Masanori Hariyama;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: May 2017, volume: 28, issue:5, pages: 1390 - 1402
Publisher: IEEE
 
» OpenFlow-Based Scalable Routing With Hybrid Addressing in Data Center Networks
Abstract:
In this letter, we propose an OpenFlow (OF)-based SCAlable Routing strategy (OSCAR) for modular data center networks (DCN) using a hybrid addressing mechanism. Each module in the DCN constitutes a segment in the network. Inter-segment routing is performed using virtual MAC (VMAC) ids assigned to the segments and intra-segment routing is done using IP addresses. OF provides central control over the network but it suffers from limited scalability in DCNs due to high control traffic. In OSCAR, the control traffic is minimized to achieve high scalability and flexibility in DCN routing.
Autors: Nabajyoti Medhi;Dilip Kumar Saikia;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1047 - 1050
Publisher: IEEE
 
» Optical Characteristics of Silicon-Based Asymmetric Vertical Nanowire Photodetectors
Abstract:
Wavelength-selective absorption phenomena of silicon-based vertical nanowire (NW) photodetectors (PDs) are investigated using 3-D numerical simulations. The difference in the refractive indexes between silicon NW and its surrounding material induces diameter-dependent waveguide effects at several specificwavelengths for asymmetric as well as symmetric structures. But the asymmetric NW PDs with a large difference in diameter between the top side and the bottom side have loss of waveguide effects. All the NWPDs achieve high external quantum efficiency (EQE) peaks with an increase in NW height. Decreasing the NW pitch or increasing the NW density also increases the EQE peak values for awide range ofwavelengths, but too densely packed NWs induce high coupling between the nearest NWs, thus losing wavelength-selective properties. Vertical NW PDs having slightly bottom-wide asymmetric structure decrease reflectance and transmittance of the incident light because of the narrow top-side and wide bottom-side silicon NW cross sections, respectively, thus achieving higher EQEs. Bottom-wide asymmetric NW PDs are promising to enhance the optical characteristics as well as to maintain waveguide properties for optical sensor applications.
Autors: Jun-Sik Yoon;Kihyun Kim;M. Meyyappan;Chang-Ki Baek;
Appeared in: IEEE Transactions on Electron Devices
Publication date: May 2017, volume: 64, issue:5, pages: 2261 - 2266
Publisher: IEEE
 
» Optimal Caching and Scheduling for Cache-Enabled D2D Communications
Abstract:
To maximize offloading gain of cache-enabled device-to-device (D2D) communications, content placement and delivery should be jointly designed. In this letter, we jointly optimize caching and scheduling policies to maximize successful offloading probability, defined as the probability that a user can obtain desired file in local cache or via D2D link with data rate larger than a given threshold. We obtain the optimal scheduling factor for a random scheduling policy that can control interference in a distributed manner, and a low complexity solution to compute caching distribution. We show that the offloading gain can be remarkably improved by the joint optimization.
Autors: Binqiang Chen;Chenyang Yang;Zixiang Xiong;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1155 - 1158
Publisher: IEEE
 
» Optimal Control for Congestion Pricing: Theory, Simulation, and Evaluation
Abstract:
This paper presents a mathematical framework for dynamic congestion pricing. The objective is to calculate an optimal toll using the optimal control theory. The problem consists of tolled lanes or routes and alternate non-tolled lanes or routes. The model is developed using a traffic conservation law, the queuing theory, and fundamental macroscopic relationships. A logit model is used for establishing the relationship between the price and the driver's choice behavior. We design a cost function and then use Hamilton–Jacobi–Bellman equation to derive an optimal control law that uses real-time information to determine an optimal tolling price. Simulations are performed to demonstrate the performance of this optimal control congestion-pricing algorithm.
Autors: Pushkin Kachroo;Saumya Gupta;Shaurya Agarwal;Kaan Ozbay;
Appeared in: IEEE Transactions on Intelligent Transportation Systems
Publication date: May 2017, volume: 18, issue:5, pages: 1234 - 1240
Publisher: IEEE
 
» Optimal Cooperative Content Caching and Delivery Policy for Heterogeneous Cellular Networks
Abstract:
To address the explosively growing demand for mobile data services in the 5th generation (5G) mobile communication system, it is important to develop efficient content caching and distribution techniques, aiming at significantly reducing redundant data transmissions and improving content delivery efficiency. In heterogeneous cellular network (HetNet), which has been deemed as a promising architectural technique for 5G, caching some popular content items at femto base-stations (FBSs) and even at user equipment (UE) can be exploited to alleviate the burden of backhaul and to reduce the costly transmissions from the macro base-stations to UEs. In this paper, we develop the optimal cooperative content caching and delivery policy, for which FBSs and UEs are all engaged in local content caching. We formulate the cooperative content caching problem as an integer-linear programming problem, and use hierarchical primal-dual decomposition method to decouple the problem into two level optimization problems, which are solved by using the subgradient method. Furthermore, we design the optimal content delivery policy, which is formulated as an unbalanced assignment problem and solved by using Hungarian algorithm. Numerical results have shown that the proposed cooperative content caching and delivery policy can significantly improve content delivery performance in comparison with existing caching strategies.
Autors: Wei Jiang;Gang Feng;Shuang Qin;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: May 2017, volume: 16, issue:5, pages: 1382 - 1393
Publisher: IEEE
 
» Optimal Data Scheduling and Admission Control for Backscatter Sensor Networks
Abstract:
This paper studies the data scheduling and admission control problem for a backscatter sensor network (BSN). In the network, instead of initiating their own transmissions, the sensors can send their data to the gateway just by switching their antenna impedance and reflecting the received RF signals. As such, we can reduce remarkably the complexity, the power consumption, and the implementation cost of sensor nodes. Different sensors may have different functions, and data collected from each sensor may also have a different status, e.g., urgent or normal, and thus we need to take these factors into account. Therefore, in this paper, we first introduce a system model together with a mechanism in order to address the data collection and scheduling problem in the BSN. We then propose an optimization solution using the Markov decision process framework and a reinforcement learning algorithm based on the linear function approximation method, with the aim of finding the optimal data collection policy for the gateway. Through simulation results, we not only show the efficiency of the proposed solution compared with other baseline policies, but also present the analysis for data admission control policy under different classes of sensors as well as different types of data.
Autors: Dinh Thai Hoang;Dusit Niyato;Ping Wang;Dong In Kim;Long Bao Le;
Appeared in: IEEE Transactions on Communications
Publication date: May 2017, volume: 65, issue:5, pages: 2062 - 2077
Publisher: IEEE
 
» Optimal Design for Offshore Wind Farm considering Inner Grid Layout and Offshore Substation Location
Abstract:
This paper introduces an efficient methodology to design optimally cable layout of inner grid as well as location of offshore substation. The methodology is composed of two optimizers: one is inner grid layout optimizer, which consists of several algorithms such as the k-clustering-based genetic algorithm, the minimum spanning tree, and the cable selection; the other one is offshore substation location optimizer based on the pattern search method. While performing iteratively two optimizers, alternatives for cable layout and candidates for location of offshore substation are generated and evaluated in the economic and reliability aspects, respectively. Optimal layout of offshore wind farm is determined so as to minimize the total cost which is a sum of construction, power loss, maintenance, and reliability costs.
Autors: Je-Seok Shin;Jin-O Kim;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 2041 - 2048
Publisher: IEEE
 
» Optimal Non-Uniform Deployments in Ultra-Dense Finite-Area Cellular Networks
Abstract:
Network densification and heterogenization through the deployment of small cellular access points (picocells and femtocells) are seen as key mechanisms in handling the exponential increase in cellular data traffic. Modeling such networks by leveraging tools from stochastic geometry has proven useful in understanding the fundamental limits imposed on network coverage and capacity by co-channel interference. Most of these works however assume infinite-sized and uniformly distributed networks on the Euclidean plane. In contrast, we study the finite-sized non-uniformly distributed networks, and find the optimal non-uniform distribution of access points, which maximizes network coverage for a given non-uniform distribution of mobile users and vice versa.
Autors: Pete Pratt;Carl P. Dettmann;Orestis Georgiou;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1139 - 1142
Publisher: IEEE
 
» Optimal Reactive Power Dispatch With Accurately Modeled Discrete Control Devices: A Successive Linear Approximation Approach
Abstract:
In this paper, a novel solution to the optimal reactive power dispatch (ORPD) problem is proposed. The nonlinearity of the power flow equations is handled by a new successive linear approximation approach. For the voltage magnitude terms, a mathematical transformation that improves the accuracy and facilitates the linear modeling of shunt capacitors is used. Without loss of accuracy, the load tap changers and shunt capacitors are both modeled by linear constraints using discrete variables, which facilitates the linearly constrained mixed-integer formulation of the proposed ORPD model. An efficient iterative solving algorithm is introduced. The obtained solution strictly satisfies the power flow equations. Case studies on several IEEE benchmark systems show that the proposed algorithm can efficiently provide near-optimal solutions with the error of the objective functions of less than 0.1%. Compared with several commercial solvers, the proposed method shows distinct advantages in terms of both robustness and efficiency. Moreover, based on the round-off results, a heuristic method that reduces the optimization ranges of the discrete control variables is proposed. This method can further improve the computational efficiency with small losses in accuracy.
Autors: Zhifang Yang;Anjan Bose;Haiwang Zhong;Ning Zhang;Qing Xia;Chongqing Kang;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 2435 - 2444
Publisher: IEEE
 
» Optimal Relay Node Placement and Flow Allocation in Underwater Acoustic Sensor Networks
Abstract:
In recent years, underwater acoustic sensor networks (UASNs) have attracted widespread attention in academia. Prolonging the network lifetime is a crucial issue for UASNs. Compared with traditional wireless sensor networks (WSNs), stringent energy becomes more critical in UASNs because the battery equipped at sensor nodes has the limited amount of energy and it is much more difficult to replace or recharge in underwater circumstance. This fact motivates us to pursue the solutions to reduce power consumption by using relay nodes and flow allocation mechanism in order to extend the network lifetime. In this paper, the issues of relay node placement and the flow allocation have been considered as a joint problem and are formulated into an integer nonlinear programming problem, which is node placement-hard in general. To solve the problem efficiently, this paper proposes a novel heuristic scheme for UASNs, which works based on a 3-D architecture. The proposed scheme consists of three algorithms, named as Alternative Flow and Relay-node Adjustment as a whole. Extensive simulation experiments demonstrate that the proposed scheme offers a simple yet attractive solution to the problem.
Autors: Lingfeng Liu;Maode Ma;Chunfeng Liu;Yantai Shu;
Appeared in: IEEE Transactions on Communications
Publication date: May 2017, volume: 65, issue:5, pages: 2141 - 2152
Publisher: IEEE
 
» Optimal Selection of Phase Shifting Transformer Adjustment in Optimal Power Flow
Abstract:
Phase shifting transformers (PSTs) can be regulated to minimize total generation cost in optimal power flow problems. Under the perception that there exists multiple optimal solutions of PST angle adjustment and better economy may be achieved by controlling a small fraction of PSTs, this letter proposes a mixed integer linear programing model to optimally determine the subset of PSTs for angle adjustment. Numerical results on several test systems including large-scale systems show that the proposed model can provide better economic dispatch with regulating a small number of PSTs.
Autors: Tao Ding;Rui Bo;Zhaohong Bie;Xifan Wang;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 2464 - 2465
Publisher: IEEE
 
» Optimal Sleep-Wake Scheduling for Energy Harvesting Smart Mobile Devices
Abstract:
In this paper, we develop optimal sleep/wake scheduling algorithms for smart mobile devices that are powered by batteries and are capable of harvesting energy from the environment. Using a novel combination of the two-timescale Lyapunov optimization approach and weight perturbation, we first design the Optimal Sleep/wake scheduling Algorithm (OSA), which does not require any knowledge of the harvestable energy process. We prove that OSA is able to achieve any system performance that is within of the optimal, and explicitly compute the required battery size, which is . We then extend our results to incorporate system information into algorithm design. Specifically, we develop the Information-aided OSA algorithm (IOSA) by introducing a novel drift augmenting idea in Lyapunov optimization. We show that IOSA is able to achieve the close-to-optimal utility performance and ensures that the required traffic buffer and energy storage size are with high probability.
Autors: Longbo Huang;
Appeared in: IEEE Transactions on Mobile Computing
Publication date: May 2017, volume: 16, issue:5, pages: 1394 - 1407
Publisher: IEEE
 
» Optimal Transport Over a Linear Dynamical System
Abstract:
We consider the problem of steering an initial probability density for the state vector of a linear system to a final one, in finite time, using minimum energy control. In the case where the dynamics correspond to an integrator ( ) this amounts to a Monge-Kantorovich Optimal Mass Transport (OMT) problem. In general, we show that the problem can again be reduced to solving an OMT problem and that it has a unique solution. In parallel, we study the optimal steering of the state-density of a linear stochastic system with white noise disturbance; this is known to correspond to a Schrödinger bridge. As the white noise intensity tends to zero, the flow of densities converges to that of the deterministic dynamics and can serve as a way to compute the solution of its deterministic counterpart. The solution can be expressed in closed-form for Gaussian initial and final state densities in both cases.
Autors: Yongxin Chen;Tryphon T. Georgiou;Michele Pavon;
Appeared in: IEEE Transactions on Automatic Control
Publication date: May 2017, volume: 62, issue:5, pages: 2137 - 2152
Publisher: IEEE
 
» Optimal WSN Deployment Models for Air Pollution Monitoring
Abstract:
Air pollution has become a major issue in the modern megalopolis because of industrial emissions and increasing urbanization along with traffic jams and the heating/cooling of buildings. Monitoring urban air quality is therefore required by municipalities and the civil society. Current monitoring systems rely on reference sensing stations that are precise but massive, costly, and, therefore, seldom. In this paper, we focus on an alternative or complementary approach, with a network of low cost and autonomic wireless sensors, aiming at a finer spatiotemporal granularity of sensing. Generic deployment models in the literature are not adapted to the stochastic nature of pollution sensing. Our main contribution is to design integer linear programming models that compute sensor deployments capturing both the coverage of pollution under time-varying weather conditions and the connectivity of the infrastructure. We evaluate our deployment models on a real data set of Greater London. We analyze the performance of the proposed models and show that our joint coverage and connectivity formulation is tight and compact, with a reasonable enough execution time. We also conduct extensive simulations to derive engineering insights for effective deployments of air pollution sensors in an urban environment.
Autors: Ahmed Boubrima;Walid Bechkit;Hervé Rivano;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: May 2017, volume: 16, issue:5, pages: 2723 - 2735
Publisher: IEEE
 
» Optimization and Analysis of Wireless Powered Multi-Antenna Cooperative Systems
Abstract:
In this paper, we consider a three-node cooperative wireless powered communication system consisting of a multi-antenna hybrid access point (H-AP) and a single-antenna relay and a single-antenna user. The energy constrained relay and user first harvest energy in the downlink and then the relay assists the user using the harvested power for information transmission in the uplink. The optimal energy beamforming vector and the time split between harvest and cooperation are investigated. To reduce the computational complexity, suboptimal designs are also studied, where closed-form expressions are derived for the energy beamforming vector and the time split. For comparison purposes, we also present a detailed performance analysis in terms of the achievable outage probability and the average throughput of an intuitive energy beamforming scheme, where the H-AP directs all the energy towards the user. The findings of the paper suggest that implementing multiple antennas at the H-AP can significantly improve the system performance, and the closed-form suboptimal energy beamforming vector and time split yields near optimal performance. Also, for the intuitive beamforming scheme, a diversity order of can be achieved, where is the number of antennas at the H-AP.
Autors: Han Liang;Caijun Zhong;Himal A. Suraweera;Gan Zheng;Zhaoyang Zhang;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: May 2017, volume: 16, issue:5, pages: 3267 - 3281
Publisher: IEEE
 
» Optimization of Capacitive Membrane Sensors for Surface-Stress-Based Measurements
Abstract:
Surface stress-based measurement is a relatively new mechanism in biological and chemical sensing. The viability of this mechanism depends on the maximum sensitivity, accuracy, and precision that can be achieved with these sensors. In this paper, an analytical approximate solution and a finite-element model are employed to describe the electromechanical behavior of a surface stress-based sensor with capacitive measurements. In the proposed model, a circular membrane is assumed as the sensing component, while only a smaller concentric circular area of its surface is subjected to a change in surface stress. The presented approximate analytical solution has a good correspondence with the finite-element model and is computationally fast and accurate enough to be an effective design tool. Based on this modeling study, we can determine the optimum design of the sensor to obtain the maximum capacitive sensitivity. Moreover, we study the effect of this optimization on the precision of the system in surface stress sensing. This paper shows that the ratio of sensing area to the whole membrane plays a key role in the overall performance of such a sensor.
Autors: Banafsheh Sajadi;Hans Goosen;Fred van Keulen;
Appeared in: IEEE Sensors Journal
Publication date: May 2017, volume: 17, issue:10, pages: 3012 - 3021
Publisher: IEEE
 
» Optimization of LDPC Codes for PIN-Based OOK FSO Communication Systems
Abstract:
For middle/short-range terrestrial high-speed free-space optical (FSO) communication systems employing ON–OFF keying (OOK) and PIN photodiode receivers, the noise distribution is symbol-dependent, and the symmetry of the underlying communication channel cannot be assumed. Therefore, this letter employs the asymmetric density evolution technique and an optimization scheme combining four different search algorithms to optimize low-density parity-check (LDPC) codes for these FSO systems. Compared with the conventional LDPC codes that are designed assuming symbols-independent symmetric channels the optimized codes are much closer to the Shannon limit for OOK modulated binary non-symmetric channels.
Autors: Jun Ao;Jiwei Liang;Chunbo Ma;Guixing Cao;Cong Li;Yufei Shen;
Appeared in: IEEE Photonics Technology Letters
Publication date: May 2017, volume: 29, issue:9, pages: 727 - 730
Publisher: IEEE
 
» Optimization of Ni(Pt)/Si-cap/SiGe Silicidation for pMOS Source/Drain Contact
Abstract:
The Ni(Pt)/Si-cap/SiGe silicidation process has been optimized by modulating the Si-cap layer thickness and a cold Si preamorphization implantation (PAI), which effectively reduces the sheet resistance (Rs). In addition, it is revealed that PAI can obviously increase the Ni(Pt)Si grain size for a lower Rs.
Autors: Lin-Lin Wang;Jian-Chi Zhang;Yu-Long Jiang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: May 2017, volume: 64, issue:5, pages: 2067 - 2071
Publisher: IEEE
 
» Optimization of Scalable Broadcast for a Large Number of Antennas
Abstract:
In this paper, for a system incorporating a large number of antennas, we address the optimal space–time coding of multimedia scalable sources, which require unequal target error rates in their bitstream. First, in terms of the number of antennas, we analyze the behavior of the crossover point of the outage probability curves for the vertical Bell Laboratories space–time (V-BLAST) architecture with a linear or a maximum-likelihood receiver, and orthogonal space–time block codes (OSTBCs). We prove that, as the number of antennas increases with the transmission data rate fixed, the crossover point in outage probability monotonically decreases. This holds for any data rate employed by the system and is valid over propagation channels such as spatially correlated Rayleigh or Rician fading channels, as well as independent and identically distributed Rayleigh channels. We next show that, over such propagation channels with a large number of antennas, those analytical results can be used to simplify the computational complexity involved with the optimal space–time coding of a sequence of scalable packets, with no performance degradation.
Autors: Seok-Ho Chang;Jihwan P. Choi;Pamela C. Cosman;Laurence B. Milstein;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 3749 - 3764
Publisher: IEEE
 
» Optimization of Signal to Noise Ratio in Silicon Nanowire ISFET Sensors
Abstract:
Inversion-mode (IM) and depletion-mode (DM) ion-sensitive field effect transistors (ISFETs) are investigated in terms of dc characteristics, pH response and low-frequency noise (LFN) characteristics. The dc characteristics show a low threshold voltage () of 28 mV for the DM ISFETs, which is preferred for the long lifetime of the pseudo-reference electrode. The DM ISFETs exhibit an enhanced pH response in the sub-threshold region, which comes from the lower sub-threshold swing. The LFN analysis for both devices shows similar level of noise equivalent current () near ; otherwise, a reduction of is obtained in the DM ISFETs in the linear region. In addition, the signal-to-noise ratio of the DM ISFETs is improved by 82.9% compared with the IM ISFETs in the sub-threshold region. Consequently, the DM ISFETs can be a better sensor platform for low-power, portable, and high-precision performance.
Autors: Hyeonsu Cho;Kihyun Kim;Jun-Sik Yoon;Taiuk Rim;M. Meyyappan;Chang-Ki Baek;
Appeared in: IEEE Sensors Journal
Publication date: May 2017, volume: 17, issue:9, pages: 2792 - 2796
Publisher: IEEE
 
» Optimization of the Close-to-Carrier Phase Noise in a CMOS–MEMS Oscillator Using a Phase Tunable Sustaining-Amplifier
Abstract:
In this paper, the phase noise of a 24-MHz complimentary metal–oxide–semiconductor microelectromechanical systems (CMOS-MEMS) oscillator with zero-level vacuum package is studied. We characterize and analyze the nonlinear regime of each one of the modules that compose the oscillator (CMOS sustaining-amplifier and MEMS resonator). As we show, the presented resonator exhibits a high nonlinear behavior. Such a fact is exploited as a mechanism to stabilize the oscillation amplitude, allowing us to maintain the sustaining-amplifier working in the linear regime. Consequently, the nonlinear resonator becomes the main close-to-carrier phase noise source. The sustaining amplifier, which functions as a phase shifter, was developed such that MEMS operation point optimization could be achieved without an increase in circuitry modules. Therefore, the system saves on area and power, and is able to improve the phase noise 26 dBc/Hz (at 1-kHz carrier frequency offset).
Autors: Guillermo Sobreviela;Martín Riverola;Francesc Torres;Arantxa Uranga;Núria Barniol;
Appeared in: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control
Publication date: May 2017, volume: 64, issue:5, pages: 888 - 897
Publisher: IEEE
 
» Optimized (2, 4) Stencil Runge–Kutta ADE-ADI FDTD With Application to Plasma
Abstract:
This paper discusses the improvement of the numerical dispersion characteristics of alternating direction implicit (ADI) finite-difference time-domain (FDTD) aimed at acquiring more accurate electromagnetic information of plasma. Through adding the optimization method, which is based on the optimization of spatial derivative to the (2, 4) stencil ADI FDTD, the optimized (2, 4) stencil ADI FDTD is proposed, and its unconditional stability is proved theoretically. The phase velocity error of the optimized (2, 4) stencil ADI FDTD versus propagation angle and grid density is investigated. In addition, the Runge–Kutta auxiliary differential equation (RKADE) scheme for tackling the constitutive relation equation of plasma is deduced, which is without additional storage occupation and computational burden compared with ADE scheme. Its numerical conductivity error is analyzed under different incident frequencies and electron collision frequencies. Through incorporating the RKADE scheme into the optimized (2, 4) stencil ADI FDTD, the optimized (2, 4) stencil RKADE-ADI FDTD is presented. The accuracy and relatively wideband capability of the proposed method is validated by two numerical experiments.
Autors: Song Wanjun;Zhang Hou;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2017, volume: 65, issue:5, pages: 2558 - 2565
Publisher: IEEE
 
» Optimized Distributed Automatic Modulation Classification in Wireless Sensor Networks Using Information Theoretic Measures
Abstract:
Automatic modulation classification of digital signals is essential for intelligent communication systems. This paper addresses the distributed classification of digital amplitude-phase modulated signals in a system of multiple sensors, which observe the unknown signal corrupted with the additive white Gaussian noise. The sensors are connected to a fusion center through block-fading orthogonal multiple access channels. We introduce a new method, where: 1) for classification, an information-theoretic similarity measure known as correntropy is exploited by each local sensor; 2) for transmitting local decisions, an estimation of probabilities is used by local sensors; and 3) for optimizing power allocation to each sensor, the Bhattacharyya distance is employed as the objective function by the fusion center. The proposed scheme improves the classification accuracy through exploiting channel diversity, which, in turn, enhances the overall performance. Simulation results validate the theoretically claimed improvement in the performance.
Autors: Saeed Hakimi;Ghosheh Abed Hodtani;
Appeared in: IEEE Sensors Journal
Publication date: May 2017, volume: 17, issue:10, pages: 3079 - 3091
Publisher: IEEE
 
» Optimized Nanocrystalline Silicon Oxide Impedance Immunosensor Electronic Tongue for Subfemtomolar Estimation of Multiple Food Toxins
Abstract:
Nanocrystalline silicon oxide (nc-SiO2) immunosensor array-based electronic tongue (E-tongue) has been recently reported to simultaneously detect multiple food toxins with subfemtomolar sensitivity. However, the quantification in these reports is quite imprecise leading to an error of more than 100%. In this paper, the quantification accuracy of multiple food toxin detection in the subfemtomolar range has been improved by more than 90% through upgraded design of the E-tongue system by incorporating two major modifications. First, the pore geometry of the nc-SiO2 immunosensors has been optimized to obtain the best combination of sensitivity, selectivity, and reproducibility through the evaluation of a figure of merit. Second, in the multivariate data processing using partial least squares discriminate analysis, additional input parameters corresponding to selectivity and standard deviations of the experimentally measured data have been incorporated. The final set of input parameters include peak frequency corresponding to maximum impedance sensitivity, bandwidth of the impedance sensitivity characteristics, cutoff frequency from noise spectroscopy, and their standard deviations. The optimized E-tongue system is capable of quantifying 0.1 fg/ml Aflatoxin B1 and Ochratoxin A with an error of only 10% and 20%, respectively, which is a remarkable achievement in the domain of food toxin detection. The proposed E-tongue system is low cost with minimal operator dependence and hence has immense potential for commercial deployment.
Autors: Hrilina Ghosh;Rahul Das;Chirasree RoyChaudhuri;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: May 2017, volume: 66, issue:5, pages: 964 - 973
Publisher: IEEE
 
» Optimizing the Quality Factor of Quartz Tuning Fork Force Sensor for Atomic Force Microscopy: Impact of Additional Mass and Mass Rebalance
Abstract:
A force sensor in the heart of an atomic force microscope (AFM) plays a key role in the AFM measurements. Quartz tuning fork (QTF) based force sensor is attracting huge attention due to its peculiar traits such as self-actuating and sensing capability, high quality factor and high force sensitivity. Unfortunately, mounting a tip on a tine of the QTF degrades its quality (Q)-factor and sensitivity. Attaching an equivalent counter mass on the opposite tine (mass rebalance) can improve the Q-factor. We investigate the impact of the attached mass and counter mass on different traits of the QTF such as Q-factor, inherent relationship between excitation voltage and output as well as shift in the resonance frequency. We propose straight forward strategies to rebalance the QTF force sensor. Experimental results demonstrate that by attaching a counter mass (at the parallel position) on the opposite tine, the tip mass can be rebalanced. Q-factor is significantly improved after mass rebalance. The increase in the Q-factor depends on the mass of the tip, counter mass and position of the counter mass relative to the position of the tip ().
Autors: Danish Hussain;Jianmin Song;Hao Zhang;Xianghe Meng;Wen Yongbing;Hui Xie;
Appeared in: IEEE Sensors Journal
Publication date: May 2017, volume: 17, issue:9, pages: 2797 - 2806
Publisher: IEEE
 
» Optomechanical Transistor With Phonons and Photons
Abstract:
A better behaved and easily controlled optical communication device could improve the performance of signal transmission. Here, we present an optomechanical transistor within cavity-optomechanical system, where the coupled phonons–photons interfere with the input signal photons while the pump field controls the transmission spectrum of the signal laser. We demonstrate the existence of transmitted signal attenuation and amplification through the optomechanical transistor when switching OFF and ON the pump field, respectively. By increasing the input pump power, the output signal gain can be further enhanced abruptly. The proposed optomechanical transistor that has the advantages of simple manufacture technology, low cost, convenient replacement, normal working environment, and so on could be implemented in current experiments and pave the way for all-optical logic circuits and quantum repeaters.
Autors: Jinjin Li;Yanhui Chu;Jinyun Liu;Ka-Di Zhu;
Appeared in: IEEE Sensors Journal
Publication date: May 2017, volume: 17, issue:10, pages: 3041 - 3044
Publisher: IEEE
 
» Orientation-Independent Catheter-Based Characterization of Myocardial Activation
Abstract:
Cardiac electrogram (EGM) signals and electrophysiologic (EP) characteristics derived from them such as amplitude and timing are central to the diagnosis and therapeutic management of arrhythmias. Bipolar EGMs are often used but possess polarity and shape dependence on catheter orientation contributing to uncertainty. Objective: We describe a novel method to map cardiac activation that resolves signals into meaningful directions and is insensitive to electrode directional effects. Methods: Multielectrode catheters that span 2- and 3-D space are used to derive local electric field (E-field) signals. A traveling wave model of local EGM propagation motivates a new “omnipolar” reference frame in which to understand EGM E-field signals and provide bipolar component EGMs aligned with these anatomic and physiologic directions. We validate the basis of this technology and determine its accuracy using a saline tank in which we simulate physiologic propagation. Results: Omnipole signals from healthy tissue are nearly free of catheter orientation effects and are constrained by biophysics to consistent morphologies and thus consistent measured amplitudes and timings. Using a 3-D EP mapping system, traveling wave treatment, and omnipolar technology (OT) E-field loops, we derived a new and nearly instantaneous means to determine conduction velocity and activation direction. Conclusion: We describe the basis of OT and validate it with ablation and mapping catheters in a saline tank. Finally, we illustrate OT with signals from live subjects. Significance: OT's novel approach with signal processing and real-time visualization allows for a newly detailed characterization of myocardial activation that is insensitive to catheter orientation.
Autors: Don Curtis Deno;Ram Balachandran;Dennis Morgan;Faiz Ahmad;Stéphane Massé;Kumaraswamy Nanthakumar;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: May 2017, volume: 64, issue:5, pages: 1067 - 1077
Publisher: IEEE
 
» Orthogonal or Superimposed Pilots? A Rate-Efficient Channel Estimation Strategy for Stationary MIMO Fading Channels
Abstract:
This paper considers channel estimation for multiple-input multiple-output (MIMO) channels and revisits two competing concepts of including training data into the transmit signal, namely, orthogonal pilot (OP) that periodically transmits alternating pilot-data symbols, and superimposed pilot (SP) that overlays pilot-data symbols over time. We investigate rates achievable by both schemes when the channel undergoes time-selective bandlimited fading and analyze their behaviors with respect to the MIMO dimension and fading speed. By incorporating the multiple-antenna factors, we demonstrate that the widely known trend in which the OP is superior to the SP in the regimes of high signal-to-noise ratio (SNR) and slow fading, and vice versa, does not hold in general. As the number of transmit antennas () increases, the range of operable fading speeds for the OP is significantly narrowed due to limited time resources for channel estimation and insufficient fading samples, which results in the SP being competitive in wider speed and SNR ranges. For a sufficiently small , we demonstrate that as the fading variation becomes slower, the estimation quality for the SP can be superior to that for the OP. In this case, the SP outperforms the OP in the slow-fading regime due to full utilization of time for data transmission.
Autors: A. Taufiq Asyhari;Stephan ten Brink;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: May 2017, volume: 16, issue:5, pages: 2776 - 2789
Publisher: IEEE
 
» Orthogonal STBC for MDL Mitigation in Mode Division Multiplexing System With MMSE Channel Estimation
Abstract:
Mode division multiplexing (MDM) has the potential of increasing the capacity of optical fiber transmission system. However, primary impaired factor mode-dependent loss (MDL) poses fundamental performance limitations. Recently MIMO space time coding technique has provided a potential solution to mitigate the MDL and hence started receiving considerable interests. In this paper, orthogonal space time block coding (OSTBC)-based MDM transmission system was investigated to test its efficiency in mitigating MDL. Considering the importance and necessity of channel estimation for coherent receivers and the paucity of literature on this subject, MMSE channel estimation process was introduced in the MDM system to test the robustness and efficiency of the OSTBC-MDM system in mitigating the MDL. Furthermore, an alternative linear decoding (LD) method was achieved by transferring the orthogonal characteristics of codes in OSTBC to the channel elements in MDM system. The LD method has the same performance as the optimal ML method, excepting that it only exhibits linear computational complexity, in terms of the number of modes and the size of constellations. Simulation results were provided to validate the efficiency and robustness of the proposed OSTBC-MDM system in mitigating the MDL in the presence of MMSE channel estimation.
Autors: Yong Qiang Hei;Wen Tao Li;Xiao Chuan Xu;Ray T. Chen;
Appeared in: Journal of Lightwave Technology
Publication date: May 2017, volume: 35, issue:10, pages: 1858 - 1867
Publisher: IEEE
 
» Outage Analysis of the Full-Duplex Decode-and-Forward Two-Way Relay System
Abstract:
Contrary to the traditional theoretical analysis with perfect self-interference cancellation, this paper studies the outage performance of a full-duplex (FD) decode-and-forward two-way relay system with the consideration of the residual self-interference incurred by the FD mode. The exact closed-form outage probability expressions are derived in this paper. In addition, the asymptotic outage performance is investigated when the transmit powers increase to infinity, and the result demonstrates that the outage probabilities monotonically increase and finally converge to 1 as the transmit power exceeds a certain threshold. Furthermore, optimal power allocation schemes and optimal relay node placement strategies are then proposed to improve the outage performance. Finally, simulation results are conducted to verify the accuracy of the theoretical analysis.
Autors: Cheng Li;Zhiyong Chen;Yafei Wang;Yao Yao;Bin Xia;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 4073 - 4086
Publisher: IEEE
 
» Outage Performance Analysis of Full-Duplex Relay-Assisted Device-to-Device Systems in Uplink Cellular Networks
Abstract:
This paper proposes a full-duplex cooperative device-to-device (D2D) communication system, where the relay employed can receive and transmit signals simultaneously. We adopt such a system to assist with D2D transmission. We first derive the conditional cumulative distribution function and the probability density function (pdf) of a series of channel parameters when the interference to the base station is taken into consideration and power control is applied at the D2D transmitter and the relay node. Then, we obtain an exact expression for the outage probability as an integral and as a closed-form expression for a special case, which can be used as a good approximation to the general case when residual self-interference is small. Additionally, we also investigate the power allocation problem between the source and the relay and formulate a suboptimal allocation problem, which we prove to be quasi-concave. Our analysis is verified by the Monte Carlo simulations, and a number of important features of full-duplex cooperative D2D communications can, thereby, be revealed.
Autors: Shuping Dang;Gaojie Chen;Justin P. Coon;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 4506 - 4510
Publisher: IEEE
 
» Outage Probability of Device to Device Communications Underlaying Cellular Network in Suzuki Fading Channel
Abstract:
Radio resource allocation in device-to-device (D2D) communications can be optimized by minimizing outage probability or maximizing throughput. In this letter, we derive two closed-form expressions for the outage probability of underlay D2D communications, by considering an additive white Gaussian noise, and large-scale and small-scale fading components. We jointly model small and large scale fading components by the Suzuki distribution and derive non-analytic integrals for the outage probability, which can be solved by Gauss–Laguerre quadrature and Gauss–Legendre quadrature numerical methods. We show that these formulas for the outage probability closely approach the simulation results. Our comparative study further shows that a low-complexity approximation belongs to the three-point Gauss–Legendre-based formula. Finally, random-based and Hungarian-based resource allocations are investigated.
Autors: Hossein Ghavami;Shahriar Shirvani Moghaddam;
Appeared in: IEEE Communications Letters
Publication date: May 2017, volume: 21, issue:5, pages: 1203 - 1206
Publisher: IEEE
 
» Output-Tracking Quantized Explicit Nonlinear Model Predictive Control Using Multiclass Support Vector Machines
Abstract:
In applications involving digital control, the set of admissible control actions is finite/quantized. Coupled with state constraints and fast dynamics, explicit model predictive control (EMPC) provides an attractive control formalism. However, the design of data-driven EMPCs with finite admissible control sets is a challenging and relatively unexplored problem. In this paper, a systematic data-driven method is proposed for the design of quantized EMPCs (Q-EMPCs) for time-varying output tracking in nonlinear systems. The design involves: 1) sampling the admissible state space using low-discrepancy sequences to provide scalability to higher dimensional nonlinear systems; 2) at each sampled data point, solving for optimal quantized model predictive control actions and determining feasibility of the intrinsic mixed-integer nonlinear programming problem; and 3) constructing the Q-EMPC control surface using multiclass support vector machines (MC-SVMs). In particular, four widely used MC-SVM algorithms are employed to construct the proposed data-driven Q-EMPC. Extensive testing and comparison among the different MC-SVM algorithms is performed on 2-D and 5-D benchmark examples to demonstrate the effectiveness and scalability of the proposed methodology.
Autors: Ankush Chakrabarty;Gregery T. Buzzard;Stanisław H. Żak;
Appeared in: IEEE Transactions on Industrial Electronics
Publication date: May 2017, volume: 64, issue:5, pages: 4130 - 4138
Publisher: IEEE
 
» Over Second Octave Power Amplifier Design Based on Resistive–Resistive Series of Continuous Class-F/F−1 Modes
Abstract:
This letter presents a novel methodology for resistive–resistive series of continuous class-F/ modes (Res.–Res. SCF/Ms) power amplifier (PA) design. The bandwidth is expanded by designing the lower band with resistive second- and third-harmonic impedances and the upper band with resistive second-harmonic impedance and reactive third-harmonic impedance using a waveform engineering method. Mathematical derivation of the methodology is described in detail. The proposed design is experimentally verified using a Res.–Res. SCF/Ms PA operating across 0.4–2.3 GHz with 62.3%–80.5% drain efficiency and 39–42 dBm output power.
Autors: Qing-Hua Tang;Yang-Hua Li;Wen-Guang Li;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: May 2017, volume: 27, issue:5, pages: 494 - 496
Publisher: IEEE
 
» Overcurrent Protection Response of a Hot Rolling Mill Filtering System: Analysis of the Process Conditions
Abstract:
This paper reproduces the abnormal operating conditions of a hot strip mill during different switching contingencies that may take place in the filtering system of the installation. Moreover, the evolution of the main electrical variables is predicted considering different characteristics of the steel to be milled. Within this work, the response of the overcurrent protection of the different filtering banks is analyzed along with different scenarios that could lead to switching operations in those filters. The analysis of the voltage stability and distortion at the point of common coupling (PCC), the evaluation of reactive power flows upstream of the PCC, the prediction of harmonic currents, and the study of the new operating conditions of the filters and the rolling stands under the said contingencies are assessed. The methodology described in this study provides the operator with important information on the expected electrical variables that can be extremely useful in deciding if the hot rolling mill can ride-through unexpected switching states of the filter banks. This forecast can avoid a good number of unscheduled stops, which could result in a significant reduction of production and economical losses.
Autors: Gonzalo Alonso Orcajo;Pablo Ardura G.;Josué Rodríguez D.;José M. Cano;Joaquín G. Norniella;Rocío Llera T.;Diego Cifrián R.;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 2596 - 2607
Publisher: IEEE
 
» Packet-Centric Tradeoff and Unfair Success Region in IEEE 802.11 WLANs
Abstract:
In this paper, we present a packet-centric analytical study of carrier sense multiple access with collision avoidance (CSMA/CA)-based medium access in wireless local area networks, specifically using the IEEE 802.11 distributed coordination function (DCF). The packet-centric viewpoint of analysis adds a new dimension of insights over those available in the existing body of knowledge in this domain. We propose an absorbing Markov chain-based model for analyzing the behavior of head-of-line frames of each station in such networks. We generalize the long-term and short-term unfairness induced by the randomness of the DCF protocol and depict the actual unfair success region to be avoided in fair resource allocation schemes. One of the primary objectives of any CSMA/CA-based medium access control (MAC) protocol is to increase the frame delivery probability, while reducing the average delay of delivery. With such considerations, we show a tradeoff relationship between the delivery probability and access delay with respect to the maximum retransmission limit in a packet-centric approach. We numerically evaluate the packet-centric behavior of the DCF protocol for single-hop single access point networks involving both the saturated and unsaturated stations, imperfect wireless channel, and varying payload sizes.
Autors: Sudip Misra;Manas Khatua;
Appeared in: IEEE Transactions on Vehicular Technology
Publication date: May 2017, volume: 66, issue:5, pages: 4223 - 4230
Publisher: IEEE
 
» Parameter Estimation of Resonant Fault Current Limiter for Protection and Stability Analysis
Abstract:
Aging or prolonged subjection to stressed conditions cause changes in the parameters of fault current limiter (FCL). These changes must be noticed to take remedial actions if necessary and to make sure whether the system fault current level is within the rated capacities of existing equipment or not. This paper presents a method for estimating parameters of a series resonant type FCL (RFCL) by using synchronized time-domain data from both ends of a transmission line. Estimated parameters during normal operation are used for protection and stability analysis of the system and fault data are used to analyze the performance of RFCL during fault. Electromagnetic transient line model is used to calculate the current and voltage across the device which are used to estimate the parameters of RFCL. PSCAD/EMTDC simulations are used to test the method. Applications of the parameter estimation method are also presented and as a demonstration, effect of variation in current limiting reactor on system transient stability is analyzed.
Autors: A. N. R. L. Sirisha;Ashok Kumar Pradhan;
Appeared in: IEEE Transactions on Power Systems
Publication date: May 2017, volume: 32, issue:3, pages: 2288 - 2295
Publisher: IEEE
 
» Parametric Planning Model for Video Quality Evaluation of IPTV Services Combining Channel and Video Characteristics
Abstract:
Parametric planning models are designed for estimating the video quality, which can be applied to effective planning, implementation, and management of network video applications and communication networks. However, different from the bitstream-based evaluation models, the planning models are not allowed to exploit the video streams, with only limited information available for use, i.e., a few general parameters predetermined by the service providers and network operators. In this paper, a parametric planning model combining channel and video characteristics is proposed to estimate the video distortion caused by packet loss for Internet protocol television (IPTV) services. More specifically, the probability distribution of the channel states is determined by detailed analysis of the channel characteristics. Then, considering the influence of burst packet loss and the temporal dependence between frames, several sequence-level and frame-level parameters for video quality evaluation are derived from the perspective of the probability distribution of the channel states. Utilizing these parameters, the proposed model approximates the video quality considering the effects of direct packet loss and error propagation. Experimental results show that the proposed model has a superior performance for video quality estimation than the three commonly used parametric planning models.
Autors: Jiarun Song;Fuzheng Yang;Yicong Zhou;Shan Gao;
Appeared in: IEEE Transactions on Multimedia
Publication date: May 2017, volume: 19, issue:5, pages: 1015 - 1029
Publisher: IEEE
 
» Partial Discreteness: A Novel Prior for Magnetic Resonance Image Reconstruction
Abstract:
An important factor influencing the quality of magnetic resonance (MR) images is the reconstruction method that is employed, and specifically, the type of prior knowledge that is exploited during reconstruction. In this work, we introduce a new type of prior knowledge, partial discreteness (PD), where a small number of regions in the image are assumed to be homogeneous and can be well represented by a constant magnitude. In particular, we mathematically formalize the partial discreteness property based on a Gaussian Mixture Model (GMM) and derive a partial discreteness image representation that characterizes the salient features of partially discrete images: a constant intensity in homogeneous areas and texture in heterogeneous areas. The partial discreteness representation is then used to construct a novel prior dedicated to the reconstruction of partially discrete MR images. The strength of the proposed prior is demonstrated on various simulated and real k-space data-based experiments with partially discrete images. Results demonstrate that the PD algorithm performs competitively with state-of-the-art reconstruction methods, being flexible and easy to implement.
Autors: Gabriel Ramos-Llordén;Arnold J. den Dekker;Jan Sijbers;
Appeared in: IEEE Transactions on Medical Imaging
Publication date: May 2017, volume: 36, issue:5, pages: 1041 - 1053
Publisher: IEEE
 
» Partial Hard Thresholding
Abstract:
We study iterative algorithms for compressed sensing that have an “orthogonalization” step at each iteration to keep the residual orthogonal to the span of those columns of the measurement matrix that have been selected so far. To unify the design and analysis of such algorithms, we propose a novel partial hard-thresholding (PHT) operator that is similar to the hard thresholding operator but restricts the amount by which the support set can change in one iteration. Using the PHT operator and its properties, we provide a general framework to prove support recovery results for iterative algorithms employing this operator as well as those employing the hard-thresholding operator. Next, based on the PHT operator, we propose a novel family of algorithms. At one end of our family of algorithms lie well-known hard thresholding algorithms iterative thresholding with inversion and hard thresholding pursuit, whereas at the other end, we get a novel algorithm that we call orthogonal matching pursuit with replacement (OMPR). Like the classic greedy algorithm OMP, OMPR too adds exactly one coordinate to the support of the iterate at each iteration based on the correlation with the current residual. However, unlike OMP, OMPR also removes one coordinate from the support. This simple change allows us to prove that OMPR has the best known guarantees for sparse recovery in terms of the restricted isometry property (RIP), a condition on the measurement matrix. In contrast, OMP is known to have very weak performance guarantees under RIP. Finally, we show that most of the existing “orthogonalized” iterative algorithms, such as CoSaMP, subspace pursuit, OMP, can be expressed using the PHT operator. As a pleasing consequence of our novel and generic results for the PHT operator, we provide the tightest known RIP analysis of all of the above-mentioned iterative algorithms: CoSaMP, subspace pursuit, and OMP.
Autors: Prateek Jain;Ambuj Tewari;Inderjit S. Dhillon;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2017, volume: 63, issue:5, pages: 3029 - 3038
Publisher: IEEE
 
» Partitioned Stator Machines With NdFeB and Ferrite Magnets
Abstract:
Partitioned stator (PS) machines employ two separated stators to accommodate armature windings and permanent magnets (PMs), respectively, alleviating the space conflict in stator-PM machines, and hence boosting the torque density. However, the PM usage volume in PS machines is relatively large, and thus the material cost is high, which is undesirable for the cost-sensitive applications. In this paper, a PS machine employing ferrite PM is presented, which takes advantage of larger available space for PMs while balances the performance and cost. The electromagnetic characteristics of an optimized ferrite PS machine and an NdFeB PS machine are evaluated together with a classic Prius2010 interior PM (IPM) machine as a baseline. Meanwhile, the economic issues are considered. The results reveal that the NdFeB PS machine has higher torque density than the Prius2010 IPM machine, but is more expensive, while the ferrite PS machine can significantly reduce the cost and still exhibit good performance. The demagnetization behavior of the ferrite PS machine is evaluated and a new method to improve the demagnetization withstand capability is proposed. Moreover, the mechanical analysis is conducted for the cupped rotor of PS machines. Finally, a pair of small-scaled prototypes are manufactured to validate the predictions.
Autors: Hao Hua;Z. Q. Zhu;C. Wang;Mei Zheng;Zhongze Wu;Di Wu;Xiao Ge;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 1870 - 1882
Publisher: IEEE
 
» Passive Tuning of Optical Couplers Using a Thin-Film Cladding Material
Abstract:
This letter reports the demonstration of a novel method to passively tune the splitting ratio of a Ti-indiffused lithium niobate (LiNbO3) 3-dB directional coupler by the addition of a silicon-rich nitride cladding material. Plasma-enhanced chemical vapor deposition of such cladding layer onto a coupler alters the effective index of the odd and even modes in the coupled waveguide. By varying the thickness of the thin-film cladding layer, we are able to precisely control the coupling ratio and compensate for variations arising from fabrication tolerances that can significantly impact coupling.
Autors: Ugochukwu J. Nsofor;Peng L. Yao;Shouyuan Shi;Dennis W. Prather;
Appeared in: IEEE Photonics Technology Letters
Publication date: May 2017, volume: 29, issue:9, pages: 775 - 778
Publisher: IEEE
 
» Past as Prolog(ue): Humans, Machines, and 20 Years of Internet Computing
Abstract:
To celebrate IEEE Internet Computing's 20th anniversary, William Regli reflects on writing the lead technical article of the inaugural issue in 1997. Some of the observations he made two decades ago, as this discipline arose, were temporal in nature, and indicative of the times. Others, however, carried a certain prescience while distilling enduring themes.
Autors: William Regli;
Appeared in: IEEE Internet Computing
Publication date: May 2017, volume: 21, issue:3, pages: 8 - 10
Publisher: IEEE
 
» Path Setup for Hybrid NoC Architectures Exploiting Flooding and Standby
Abstract:
Future many-core systems will require energy-efficient, high-throughput and low-latency communication architectures. Silicon Photonics appears today a promising solution towards these goals. The inability of photonics networks to perform inflight buffering and logic computation suggests the use of hybrid photonic-electronic architectures. In order to exploit the full potential of photonics, it is essential to carefully design the path-setup architecture, which is a primary source of performance degradation and power consumption. In this paper, we propose a new path-setup approach which can put allocated circuits in a stand-by state, rapidly restoring them when needed. Path-setup messages are sent using a flooding routing strategy to enhance the possibility of finding free optical paths. We compare the proposed approach with a commonly used path-setup strategy as well as some other alternatives available. The results exhibit encouraging improvements in terms of both performance and energy consumption.
Autors: Edoardo Fusella;José Flich;Alessandro Cilardo;
Appeared in: IEEE Transactions on Parallel and Distributed Systems
Publication date: May 2017, volume: 28, issue:5, pages: 1403 - 1416
Publisher: IEEE
 
» Patient-Specific Finite-Element Simulation of the Insertion of Guidewire During an EVAR Procedure: Guidewire Position Prediction Validation on 28 Cases
Abstract:
Objective: Validation of a numerical method to compute arterial deformations under the insertion of an “extra-siff” guidewire during Endovascular Repair of Abdominal Aortic Aneurysm. Methods: We propose the validation of a previously developed simulation method. The model is calibrated using anatomical hypothesis and intraoperative observations. Simulation results are blindly evaluated against 3-D imaging data acquired during the surgical procedure on 28 patients, based on the predicted position of the intraoperative guidewire. Results: Simulation was successfully conducted on the 28 patients. The mean position error given by the Modified Hausdorff Distance for the 28 cases was 3.8 ± 1.9 mm, which demonstrates very good results for most of the cases. Conclusion: The work reported here shows that numerical simulation can predict some rather large variations in the vascular geometry due to tools insertion, for a wide variety of aorto-iliac morphologies. This is a new step toward clinically applicable mechanical simulation. Significance: Validation on 3-D intraoperative data on a large number of cases—robustness on adverse anatomies.
Autors: J. Gindre;A. Bel-Brunon;M. Rochette;A. Lucas;A. Kaladji;P. Haigron;A. Combescure;
Appeared in: IEEE Transactions on Biomedical Engineering
Publication date: May 2017, volume: 64, issue:5, pages: 1057 - 1066
Publisher: IEEE
 
» Pattern Reconfigurable Antenna Based on Morphing Bistable Composite Laminates
Abstract:
In this paper, a novel pattern reconfigurable antenna based on morphing bistable composite laminates is presented. The bistable asymmetric glass-fiber reinforced polymer (GFRP) composite laminates have two stable configurations with curvatures of opposite signs. The antenna pattern is reconfigured by transforming the configuration of the bistable GFRP laminate which acts as the substrate of the antenna. The coplanar waveguide transmission lines feeding technique is used for the microstrip quasi-Yagi antenna. A prototype of the proposed antenna is fabricated using a semi-automatic screen printer and an autoclave. The transformation between the two stable states of the proposed antenna using Ni/Ti shape memory alloy springs is investigated experimentally. The out-of-plane displacements, reflection coefficients and radiation patterns for the two stable configurations of the antenna are measured, which agree well with the simulated results. The main beam direction is 89° and 59° for the two stable configurations, respectively. In addition, the influences of various bending radii on the radiation patterns are investigated to gain a thorough understanding of the reconfigurable mechanism of the proposed antenna. Finally, a two-element array of such an antenna is presented and measured. The proposed antenna provides a potential application in multifunctional, conformal, morphing, and integrated structures.
Autors: Jianqiang Hu;Shu Lin;Fuhong Dai;
Appeared in: IEEE Transactions on Antennas and Propagation
Publication date: May 2017, volume: 65, issue:5, pages: 2196 - 2207
Publisher: IEEE
 
» PBL-SEE: An Authentic Assessment Model for PBL-Based Software Engineering Education
Abstract:
The problem-based learning (PBL) approach has been successfully applied to teaching software engineering thanks to its principles of group work, learning by solving real problems, and learning environments that match the market realities. However, the lack of well-defined methodologies and processes for implementing the PBL approach represents a major challenge. The approach requires great flexibility and dynamism from all involved, whether in mapping content, in teacher performance, or laying out the process of how learners should go about solving problems. This paper suggests that management processes can help in implementing PBL throughout its life cycle (planning, implementation, monitoring, and enhancement), and proposes an assessment model called PBL-SEE for use in software engineering education (SEE). Two examples of its use are provided. The results show how the model can be applied and how the resulting information can be used to make the PBL initiatives “authentic,” in that they bring the reality of the labor market to the learning environment, while keeping to PBL principles.
Autors: Simone C. dos Santos;
Appeared in: IEEE Transactions on Education
Publication date: May 2017, volume: 60, issue:2, pages: 120 - 126
Publisher: IEEE
 
» PBTI Investigation of MoS2 n-MOSFET With Al2O3 Gate Dielectric
Abstract:
For the first time, we report the positive bias temperature instability of the back gated multilayer MoS2 n-MOSFETs with Al2O3 gate dielectric. In the stress phase, the – curve shifts to the positive gate bias. In the recovery phase, it shifts back to the negative gate bias. After 5000 s recovery, it completely recovers to that of the fresh device. The results indicate that the voltage shift is solely due to trapping and detrapping of the pre-existing border traps in the Al2O3 dielectric. The traps consist of fast and slow components with the capture time constants of 7 and s and the emission time constants of 15 and s, respectively. The results from first-order trapping and detrapping calculations are in overall agreements with 12 measured curves including six under stress voltages and six in the recovery phases. The energy densities for the fast and slow traps are derived to be in the order of 1013 cm eV above the bottom of the MoS2 conduction band.
Autors: Hui-Wen Yuan;Hui Shen;Jun-Jie Li;Jinhai Shao;Daming Huang;Yi-Fang Chen;P. F. Wang;S. J. Ding;Albert Chin;Ming-Fu Li;
Appeared in: IEEE Electron Device Letters
Publication date: May 2017, volume: 38, issue:5, pages: 677 - 680
Publisher: IEEE
 
» Peer-to-Peer Indoor Navigation Using Smartphones
Abstract:
Most of existing indoor navigation systems work in a client/server manner, which needs to deploy comprehensive localization services together with precise indoor maps a prior. In this paper, we design and realize a peer-to-peer navigation system (ppNav), on smartphones, which enables the fast-to-deploy navigation services, avoiding the requirements of pre-deployed location services and detailed floorplans. ppNav navigates a user to the destination by tracking user mobility, promoting timely walking tips and alerting potential deviations, according to a previous traveller’s trace experience. Specifically, we utilize the ubiquitous WiFi fingerprints in a novel diagrammed form and extract both radio and visual features of the diagram to track relative locations and exploit fingerprint similarity trend for deviation detection. We further devise techniques to lock on a user to the nearest reference path in case he/she arrives at an uncharted place. Consolidating these techniques, we implement ppNav on commercial mobile devices and validate its performance in real environments. Our results show that ppNav achieves delightful performance, with an average relative error of 0.9 m in trace tracking and a maximum delay of nine samples (about 4.5 s) in deviation detection.
Autors: Zuwei Yin;Chenshu Wu;Zheng Yang;Yunhao Liu;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: May 2017, volume: 35, issue:5, pages: 1141 - 1153
Publisher: IEEE
 
» Perceptual Spatial Audio Recording, Simulation, and Rendering: An overview of spatial-audio techniques based on psychoacoustics
Abstract:
Developments in immersive audio technologies have been evolving in two directions: physically motivated systems and perceptually motivated systems. Physically motivated techniques aim to reproduce a physically accurate approximation of desired sound fields by employing a very high equipment load and sophisticated, computationally intensive algorithms. Perceptually motivated techniques, however, aim to render only the perceptually relevant aspects of the sound scene by means of modest computational and equipment load. This article presents an overview of perceptually motivated techniques, with a focus on multichannel audio recording and reproduction, audio source and reflection culling, and artificial reverberators.
Autors: Huseyin Hacihabiboglu;Enzo De Sena;Zoran Cvetkovic;James Johnston;Julius O. Smith III;
Appeared in: IEEE Signal Processing Magazine
Publication date: May 2017, volume: 34, issue:3, pages: 36 - 54
Publisher: IEEE
 
» Performance Analysis and Optimization for SWIPT Wireless Sensor Networks
Abstract:
This paper investigates and optimizes the performance of simultaneous wireless information and power transfer (SWIPT) in wireless sensor networks over Nakagami- fading channels. In the considered system, there is one mobile reader (), which is equipped with one transmit antenna and one receive antenna, and a group of passive sensors. The information delivery includes two stages: 1) broadcasts a command with radio-frequency energy to the sensors, which adopt time splitting (TS)/power splitting (PS) schemes to harvest energy and 2) sensors deliver their information to over orthogonal channels by using the harvested energy. In this paper, we propose a unified framework to study and optimize the impact of SWIPT on the system performance with both TS and PS schemes. First, we characterize the probability density function and cumulative distribution function of the signal-to-interference-plus-noise-ratio in high signal-to-noise ratio region, then we study the outage and ergodic capacity performance of the backward links. The approximated closed-form expressions for the outage probability and ergodic capacity are derived and validated through Monte Carlo simulations. Finally, we also evaluate the energy efficiency of the target system, and propose an optimal splitting scheme for TS and PS to maximize the throughput of the target system.
Autors: Gaofeng Pan;Hongjiang Lei;Yi Yuan;Zhiguo Ding;
Appeared in: IEEE Transactions on Communications
Publication date: May 2017, volume: 65, issue:5, pages: 2291 - 2302
Publisher: IEEE
 
» Performance Analysis of Receive Space Modulation in the Shadowing MIMO Broadcast Channel
Abstract:
In this paper, the performance analysis of Receive Space Modulation (RSM) in the shadowing Multiple-Input Multiple-Output (MIMO) broadcast channel is presented. This is undertaken by considering Zero Forcing (ZF) precoding and both small and large scale fading. In particular, a closed form and accurate framework for the evaluation of the Symbol Error Rate (SER) is derived. In addition, the diversity order and the coding gain of the new architecture are also obtained. The derived framework can be directly extended to the conventional spatially multiplexed shadowing MIMO broadcast channel. It is shown that RSM achieves the same diversity order and, in certain scenarios which are well defined, higher coding gain than spatially multiplexing (SMX). Also, the performance difference between RSM and SMX in the shadowing broadcast channel is mathematically quantified. Finally, numerical results that verify the new framework and conclusions are provided.
Autors: Athanasios Stavridis;Marco Di Renzo;Peter M. Grant;Harald Haas;
Appeared in: IEEE Transactions on Communications
Publication date: May 2017, volume: 65, issue:5, pages: 1972 - 1983
Publisher: IEEE
 
» Performance Analysis of TanDEM-X Quad-Polarization Products in Pursuit Monostatic Mode
Abstract:
Since 2010, the two twin synthetic aperture radar (SAR) satellites TerraSAR-X and TanDEM-X have been acquiring high-resolution images to generate a global Earth's digital elevation model (DEM). Both satellites have been flying in a controlled close orbit formation, acquiring data in the nominal bistatic stripmap single-polarization mode. Once the acquisition of the dataset for the generation of the DEM has been completed, the flexibility offered by both SAR instruments in terms of interferometric, imaging, and polarization modes has been further exploited to demonstrate the different capabilities of the TanDEM-X experimental modes. By activating the dual-receive antenna mode, full polarimetric data can be acquired. For the first time, it has been possible to systematically command quad-polarization acquisitions in a dedicated TanDEM-X mission science phase, started in October 2014. In this paper, we present a first performance analysis and quality assessment of such quad-polarization products. The SAR image resolution and the noise equivalent sigma zero have been evaluated to show the quality of the focused SAR products. The influence of different instrument parameters on the SAR and interferometric performance, such as chirp bandwidth, pulse repetition frequency, or block adaptive quantization, has been investigated as well. For the evaluation of the interferometric performance, key parameters such as coherence and interferometric phase error have been analyzed. In this paper, the obtained results are presented and recommendations are given for the optimization in the commanding of TanDEM-X quad-polarization acquisitions.
Autors: José-Luis Bueso-Bello;Michele Martone;Pau Prats-Iraola;Carolina González-Chamorro;Thomas Kraus;Jens Reimann;Marc Jäger;Benjamin Bräutigam;Paola Rizzoli;Manfred Zink;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: May 2017, volume: 10, issue:5, pages: 1853 - 1869
Publisher: IEEE
 
» Performance and Stability Benchmarking of Monolithic 3-D Logic Circuits and SRAM Cells With Monolayer and Few-Layer Transition Metal Dichalcogenide MOSFETs
Abstract:
For the first time, considering the architecture of monolithic 3-D integration, we evaluate and benchmark the performance of 3-D logic circuits and stability/performance of 3-D 6T SRAM cells with monolayer and few-layer transition metal dichalcogenide (TMD) devices based on ITRS 2028 (5.9 nm) technology node. The impact of random variations on the cell stability is also investigated. With the possibility of adopting monolayer or few-layer TMDs for nFET- and pFET-tiers enabled by monolithic 3-D integration, this paper indicates that the trilayer TMD device may substantially degrade the performance of 3-D logic circuits in spite of its higher mobility. This paper also reveals that stacking the monolayer pFET-tier over the bilayer nFET-tier may provide better nominal stability and read/write performance for 6T superthreshold SRAM compared with the planar technology, whereas the optimum 3-D configuration for near-/sub-threshold operations appears to be the monolayer pFET-tier over the monolayer nFET-tier. Besides the 6T cell structure, 8T SRAM cells are also investigated with monolithic 3-D integration for near-threshold/subthreshold operation. The monolayer nFET-tier over the bilayer pFET-tier configuration is shown to be the optimum 3-D 8T near-threshold/subthreshold cell design.
Autors: Chang-Hung Yu;Pin Su;Ching-Te Chuang;
Appeared in: IEEE Transactions on Electron Devices
Publication date: May 2017, volume: 64, issue:5, pages: 2445 - 2451
Publisher: IEEE
 
» Performance Enhancement of MEMS-Based INS/UWB Integration for Indoor Navigation Applications
Abstract:
Inertial navigation system (INS) has an increasingly important role in indoor navigation, which mainly uses inertial measurement units based on a micro electro mechanical system (MEMS) to acquire data, and which is independent of the external environment. However, INS has serious accumulated errors, and thus, it was often integrated with wireless location systems (WLSs), such as ultra wideband (UWB) system, in order to enhance the position performance. Namely, MEMS-based inertial sensors have the problem of random errors. Besides, a UWB system is vulnerable to external environment conditions, such as the non-line-of-sight (NLOS) factor and multipath effects, and thus, many outliers are produced. In order to improve the overall performance of the INS/UWB system, this paper proposes the three-tier approach based on: 1) analysis and pre-filtering of random errors of MEMS-based inertial sensors, and use of a complementary filter to provide attitude information of navigation system; 2) use of the anti-magnetic ring (AMR) to eliminate the outliers from the UWB system in NLOS environment; and 3) improvement of positioning accuracy at information fusion level using the double-state adaptive Kalman filter. The proposed approach was verified by experiments that included AMR test and filter test. The obtained results have validated the proposed method efficiency.
Autors: Qigao Fan;Biwen Sun;Yan Sun;Xiangpeng Zhuang;
Appeared in: IEEE Sensors Journal
Publication date: May 2017, volume: 17, issue:10, pages: 3116 - 3130
Publisher: IEEE
 
» Performance Evaluation of Bilayer Graphene Nanoribbon Tunnel FETs for Digital and Analog Applications
Abstract:
The recent advancement in the fabrication of narrow graphene nanoribbon with smooth edges has catalyzed the growth of nanoribbon based transistors. Motivated by these advances, we suggest bilayer graphene nanoribbon tunnel field-effect transistors (BLGNR-TFETs) for low voltage digital and analog applications. The device performance is analyzed by quantum transport simulation, based on self-consistent solutions of two-dimensional Poisson's equation and nonequilibrium Green's function formalism. The results indicate that the use of BLGNR-TFET instead of monolayer graphene nanoribbon TFET with very narrow width, increases the ON current and reduces the intrinsic device delay without lowering the ON/OFF current ratio. The BLGNR-TFET for analog/RF applications has provided higher intrinsic gain at very narrow ribbon width; however, very narrow width reduces the cutoff frequency. Furthermore, RF figure of merits are investigated in the presence of external parasitics.
Autors: Brajesh Rawat;Roy Paily;
Appeared in: IEEE Transactions on Nanotechnology
Publication date: May 2017, volume: 16, issue:3, pages: 411 - 416
Publisher: IEEE
 
» Performance Evaluation of Self Backhauled Small Cell Heterogeneous Networks
Abstract:
We compare the performance of heterogeneous networks (HetNets) with self backhauled small cells (SBSCs) relative to those with wired backhaul based small cells (WBSCs). The comparisons are made for a variety of SBSC based HetNets including: 1) when the HetNets employ omni antennas at the SBSCs and Uniform PF at the macro; 2) with directional antennas at the SBSCs and uniform PF at the macro; 3) with directional antennas at the SBSCs and weighted PF at the macro; and 4) with Directional antennas at the SBSCs and QoS-aware PF at the macro. The study catalogs our learning experiences with SBSC HetNets, leading the reader through the sequence of enhancements made to improve the performance of SBSC HetNets relative to WBSC HetNets.
Autors: Matthew Andrews;Arunabha Ghosh;Rahul N. Pupala;Subramanian Vasudevan;
Appeared in: IEEE Transactions on Wireless Communications
Publication date: May 2017, volume: 16, issue:5, pages: 3102 - 3110
Publisher: IEEE
 
» Performance Evaluation of the Triangle-Based Empirical Soil Moisture Relationship Models Based on Landsat-5 TM Data and In Situ Measurements
Abstract:
Surface soil moisture (SSM) is an important parameter at the land-atmosphere interface. In past decades, passive microwave remote sensing offers a good opportunity for obtaining SSM on a global scale, and many downscaling methods have been proposed using the triangle-based empirical soil moisture relationship models to overcome the limitation of coarse spatial resolution of its SSM products for regional applications. This paper aimed to examine and compare the effectiveness of five typical triangle-based empirical soil moisture relationship models for estimating SSM with Landsat-5 data and in situ measurements from the Maqu network on the northeastern part of the Tibetan Plateau for nine cloud-free days. The results showed that the model that treats the SSM as a second-order polynomial with land surface temperature, vegetation indices (VIs), and surface albedo as inputs exhibited the best performance compared with the results of other models. The VI comparison indicated that the use of the normalized difference VI or the fractional vegetation cover in this model outperformed other VIs, with the root-mean-square deviation of approximately 0.055 m3/m3 and the coefficient of determination ($text{R}^{2}$ ) above 0.78 at the nine-day average level. In addition, a significant spatial scale effect of the model was also found through analyzing the model fitting results at different window sizes. The study provides important insight into the best empirical relationship models for capturing soil moisture dynamics. These models can support the passive microwave soil moisture data spatial downscaling and validation applications in future studies.
Autors: Wei Zhao;Ainong Li;Huaan Jin;Zhengjian Zhang;Jinhu Bian;Gaofei Yin;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: May 2017, volume: 55, issue:5, pages: 2632 - 2645
Publisher: IEEE
 
» Performance Improvement and Current Collapse Suppression of Al2O3/AlGaN/GaN HEMTs Achieved by Fluorinated Graphene Passivation
Abstract:
In this letter, fluorinated graphene (FG) is utilized to passivate GaN surface for a metal–insulator–semiconductor high electron mobility transistor (MIS HEMT). The FG-MIS HEMT achieves better DC characteristics than a traditional MIS HEMT, including larger saturation drain current density (34.3%), higher peak trans-conductance (14.4%), lower ON-resistance (21.6%), and lower off-state leakage. Moreover, current collapse measurement reveals that not only can FG suppress the drain saturation current reduction of MIS HEMT from 41.8% to 8.1% at off-state drain bias of 50 V, but also it prevents dynamic ON-resistance increasing with off-state stress. The coverage of FG on GaN surface can prevent GaN being oxidized and N diffusion from GaN during gate dielectric deposition, thus suppressing the formation of Ga-O bonds and Ga dangling bonds, leading to an excellent interface condition for Al2O3/GaN with reduced fixed interface charges. Therefore, significant passivation effect is achieved.
Autors: Lingyan Shen;Dongliang Zhang;Xinhong Cheng;Li Zheng;Dawei Xu;Qian Wang;Jingjie Li;Duo Cao;Yuehui Yu;
Appeared in: IEEE Electron Device Letters
Publication date: May 2017, volume: 38, issue:5, pages: 596 - 599
Publisher: IEEE
 
» Performance Investigation of a Nonlinear Energy Harvester With Random Vibrations and Subthreshold Deterministic Signals
Abstract:
In the field of energy harvesting, it has been demonstrated that under the appropriate conditions, nonlinear configurations of the harvester can provide better performance, compared with linear resonant oscillators; the performance is quantified in terms of the amount of energy extracted from environmental mechanical or seismic vibrations. In this paper, the results of investigations on a system for energy harvesting from wideband vibrations, using a nonlinear snap-through-buckling configuration and two piezoelectric actuators, placed at the stable minima of the potential energy function that underpins the dynamics of the flexible beam are presented. A nonlinear model is proposed that can describe the device behavior when it is driven by a suprathreshold deterministic signal, a wideband noise, or a subthreshold signal superimposed onto a (usually bandlimited) noise background. In the latter case, the system is seen to exhibit the so-called “stochastic resonance” behavior. The bandwidth of the nonlinear energy harvester is about 15 Hz, which is compatible with vibrational energy sources at low frequencies, e.g., a walking human. The device is seen to generate power up to when subject to a noise limited at 15 Hz. The power is sufficient to operate a standard wireless sensor node and the conversion efficiency of the harvester is about 12%.
Autors: Bruno Andò;Salvatore Baglio;Vincenzo Marletta;Antonio Pistorio;Adi R. Bulsara;
Appeared in: IEEE Transactions on Instrumentation and Measurement
Publication date: May 2017, volume: 66, issue:5, pages: 992 - 1001
Publisher: IEEE
 
» Performance Limit Projection of Germanane Field-Effect Transistors
Abstract:
Here we explore the performance limit of monolayer germanane (GeH) field-effect transistors (FETs). We first plotted an electronic band structure of GeH using density functional theory and then tight-binding parameters were extracted. Device characteristics of GeH FETs are investigated using rigorous self-consistent atomistic quantum transport simulations within tight-binding approximations. Our simulation results indicate that GeH FETs can exhibit exceptional on-state device characteristics, such as high (>2 mA/) and large (~7 mS/) with V due to the very light effective mass of GeH (0.07m0), while maintaining excellent switching characteristics (SS ~64 mV/dec). We have also performed a scaling study by varying the channel length, and it turned out that GeH FET can be scaled down to ~14-nm channel without facing significant short channel effects but it may suffer from large leakage current at the channel length shorter than 10 nm. Finally, we have benchmarked GeH FET against MoS2 counterpart, exhibiting better suitability of GeH device for high-performance applications compared with MoS2 transistors.
Autors: AbdulAziz AlMutairi;Yiju Zhao;Demin Yin;Youngki Yoon;
Appeared in: IEEE Electron Device Letters
Publication date: May 2017, volume: 38, issue:5, pages: 673 - 676
Publisher: IEEE
 
» Performance of a Nano-CNC Machined 220-GHz Traveling Wave Tube Amplifier
Abstract:
We report on hot test measurements of a wide-bandwidth, 220-GHz sheet beam traveling wave tube amplifier developed under the Defense advanced research projects agency (DARPA) HiFIVE program. Nano-computer numerical control (CNC) milling techniques were employed for the precision fabrication of double vane, half-period staggered interaction structures achieving submicrometer tolerances and nanoscale surface roughness. A multilayer diffusion bonding technique was implemented to complete the structure demonstrating wide bandwidth (>50 GHz) with an insertion loss of about −5 dB achieved during transmission measurements of the circuit. The sheet beam electron gun utilized nanocomposite scandate tungsten cathodes that provided over 438-A/cm2 current density in the 12.5:1 ratio sheet beam. An InP HBT-based monolithic microwave integrated circuit preamplifier was employed for TWT gain measurements in the stable amplifier operation region. In the wide-bandwidth operation mode (for gun voltage of 20.9 kV), a gain of over 24 dB was measured over the frequency range of 207–221 GHz. In the high-gain operation mode (for gun voltage of 21.8 kV), over 30 dB of gain was measured over the frequency range of 197–202 GHz. High-power tests were conducted employing an extended interaction klystron.
Autors: Anisullah Baig;Diana Gamzina;Takuji Kimura;John Atkinson;Calvin Domier;Branko Popovic;Logan Himes;Robert Barchfeld;Mark Field;Neville C. Luhmann;
Appeared in: IEEE Transactions on Electron Devices
Publication date: May 2017, volume: 64, issue:5, pages: 2390 - 2397
Publisher: IEEE
 
» Performance of Minimum Mean-Square Error Beam Forming for Polarimetric Phased Array Weather Radar
Abstract:
In this paper, the development of a polarimetric phased array weather radar, which consists of a dual-polarized antenna with 2-D circular planar phase-array elements, is discussed. The radar is capable of measuring the 3-D rainfall distribution in less than several tens of seconds. Digital beamforming (DBF) is an important component in the development process of the phased array radar. In this paper, precipitation radar signal simulations are performed taking into consideration radar concepts in order to discuss the estimation accuracy of polarimetric precipitation profiles (differential reflectivity, specific differential phase, and copolar correlation coefficient) with two DBF methods that are based on Fourier and minimum mean-square error (MMSE) methods. A comparison of the performance of the two methods indicates that MMSE is superior in accuracy because of the effect of a stable and a robust main lobe and adaptively suppressed side lobes. MMSE also provides precipitation measurements eliminating the directional dependence of a beam pattern for improving the accuracy of measurements. It is also shown that the estimated accuracies of the precipitation profiles are almost independent of the number of pulses.
Autors: Hiroshi Kikuchi;Ting Wu;Eiichi Yoshikawa;Tomoo Ushio;Hideto Goto;Fumihiko Mizutani;Masakazu Wada;V. Chandrasekar;
Appeared in: IEEE Transactions on Geoscience and Remote Sensing
Publication date: May 2017, volume: 55, issue:5, pages: 2757 - 2770
Publisher: IEEE
 
» Performance of Silicone Rubber Insulators Under Thermal and Electrical Stress
Abstract:
In recent times, high temperature vulcanized (HTV) silicone rubber insulators (SIR) are being widely used for overhead high voltage transmission and distribution systems. However, over a period, the insulator surface will be exposed to high temperature in several places, particularly in desert areas; further accumulation of pollutants can alter the temperature distribution along the insulator. In the present work, long-term electrothermal experimentation is carried out on various types of full-scale insulator units. The effect of temperature on pollution performance of SIR insulators is studied, and a novel and simple methodology to achieve uniform contamination layer on inherently hydrophobic HTV SIR insulator samples is presented. A specially fabricated oven having a provision for high voltage connection and facility for measurement of leakage currents is provided. Furthermore, study of migration of low molecular weight, recovery trends of hydrophobicity, and changes in material properties using scanning electron microscopy Fourier transform infrared spectroscopy is carried out.
Autors: Rahul Chakraborty;Subba Reddy B;
Appeared in: IEEE Transactions on Industry Applications
Publication date: May 2017, volume: 53, issue:3, pages: 2446 - 2454
Publisher: IEEE
 
» Permanent and Transient Fault Tolerance for Reconfigurable Nano-Crossbar Arrays
Abstract:
This paper studies fault tolerance in switching reconfigurable nano-crossbar arrays. Both permanent and transient faults are taken into account by independently assigning stuck-open and stuck-closed fault probabilities into crosspoints. In the presence of permanent faults, a fast and accurate heuristic algorithm is proposed that uses the techniques of index sorting, backtracking, and row matching. The algorithm’s effectiveness is demonstrated on standard benchmark circuits in terms of runtime, success rate, and accuracy. In the presence of transient faults, tolerance analysis is performed by formally and recursively determining tolerable fault positions. In this way, we are able to specify fault tolerance performances of nano-crossbars without relying on randomly generated faults that is relatively costly regarding that the number of fault distributions in a crossbar grows exponentially with the crossbar size.
Autors: Onur Tunali;Mustafa Altun;
Appeared in: IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems
Publication date: May 2017, volume: 36, issue:5, pages: 747 - 760
Publisher: IEEE
 
» PERMIT: Network Slicing for Personalized 5G Mobile Telecommunications
Abstract:
5G mobile systems are expected to meet different strict requirements beyond the traditional operator use cases. Effectively, to accommodate needs of new industry segments such as healthcare and manufacturing, 5G systems need to accommodate elasticity, flexibility, dynamicity, scalability, manageability, agility, and customization along with different levels of service delivery parameters according to the service requirements. This is currently possible only by running the networks on top of the same infrastructure, the technology called network function virtualization, through this sharing of the development and infrastructure costs between the different networks. In this article, we discuss the need for the deep customization of mobile networks at different granularity levels: per network, per application, per group of users, per individual users, and even per data of users. The article also assesses the potential of network slicing to provide the appropriate customization and highlights the technology challenges. Finally, a high-level architectural solution is proposed, addressing a massive multi-slice environment.
Autors: Tarik Taleb;Badr Mada;Marius-Iulian Corici;Akihiro Nakao;Hannu Flinck;
Appeared in: IEEE Communications Magazine
Publication date: May 2017, volume: 55, issue:5, pages: 88 - 93
Publisher: IEEE
 
» Personalized Assessment as a Means to Mitigate Plagiarism
Abstract:
Although every educational institution has a code of academic honesty, they still encounter incidents of plagiarism. These are difficult and time-consuming to detect and deal with. This paper explores the use of personalized assessments with the goal of reducing incidents of plagiarism, proposing a personalized assessment software framework through which each student receives a unique problem set. The framework not only auto-generates the problem set but also auto-marks the solutions when submitted. The experience of using this framework is discussed, from the perspective of both students and staff, particularly with respect to its ability to mitigate plagiarism. A comparison of personalized and traditional assignments in the same class confirms that the former had far fewer observed plagiarism incidents. Although personalized assessment may not be cost-effective in all courses (such as language courses), it still can be effective in areas such as mathematics, engineering, science, and computing. This paper concludes that personalized assessment is a promising approach to counter plagiarism.
Autors: Sathiamoorthy Manoharan;
Appeared in: IEEE Transactions on Education
Publication date: May 2017, volume: 60, issue:2, pages: 112 - 119
Publisher: IEEE
 
» Pervasive Floorplan Generation Based on Only Inertial Sensing: Feasibility, Design, and Implementation
Abstract:
Mobile crowdsourcing is deemed as a powerful technique to solve traditional problems. But the crowdsourced data from smartphones are generally low quality, which can induce crucial challenges and hurt the applicability of crowdsourcing applications. This paper presents our study to address such challenges in a concrete application, namely, floorplan generation. Existing proposals mostly rely on infrastructural references or accurate data sources, which are restricted in terms of applicability and pervasiveness. Our proposal called SenseWit is motivated by the observation that people’s behavior offers meaningful clues for location inference. The noise, ambiguity, and behavior diversity contained in the crowdsourced data, however, mean non-trivial challenges in generating high-quality floorplans. We propose: 1) a novel concept called Nail to identify featured locations in indoor space and 2) a heuristic pathlet bundling algorithm to progressively discover the internal layouts of a floorplan. We implement SenseWit and conduct real-world experiments in different spaces to demonstrate its efficacy. This paper offers an efficient technique to obtain high-quality structures (either logical or physical) from low-quality data. We believe it can be generalized to other crowdsourcing applications.
Autors: Yuan He;Jiaqi Liang;Yunhao Liu;
Appeared in: IEEE Journal on Selected Areas in Communications
Publication date: May 2017, volume: 35, issue:5, pages: 1132 - 1140
Publisher: IEEE
 
» Peter Hilton on Naming
Abstract:
Host Felienne Hermans talks with Peter Hilton about why naming is much harder than we think, why it matters in programming and program comprehension, and how to improve your naming skills.
Autors: Felienne Hermans;
Appeared in: IEEE Software
Publication date: May 2017, volume: 34, issue:3, pages: 117 - 120
Publisher: IEEE
 
» Phase Noise Estimation and Suppression for PDM CO-OFDM/OQAM Systems
Abstract:
Phase noise induced common phase error and inter-carrier-interference are serious impairments for coherent optical orthogonal frequency-division multiplexing (CO-OFDM) systems. As have been discussed in previous publications, extra signal-to-noise-ratio (SNR) penalty is required to maintain the system performance under the interference of laser phase noise. The SNR penalty is proportional to the laser linewidth, the time duration of an OFDM symbol, and the system SNR. Therefore, the phase noise induced interference remains the bottleneck for CO-OFDM systems, especially for those systems employing high-order modulation formats, or with long fast Fourier transform window. Thanks to the usage of specially designed filter banks, CO-OFDM/offset quadrature amplitude modulation (CO-OFDM/OQAM) systems demonstrate lower out-of-band leakage and higher spectral efficiency compared with conventional CO-OFDM systems. Recently, both theoretical studies and experimental demonstrations for CO-OFDM/OQAM systems have been widely reported. With the relaxation of orthogonal condition from the complex field to the real field, phase noised induced interference in CO-OFDM/OQAM systems is more complicated than that in conventional CO-OFDM systems. To our best knowledge, there have been no studies on the phase noise estimation and suppression methods for CO-OFDM/OQAM systems. In this paper, we systematically study and analyze phase noise induced interference for CO-OFDM/OQAM systems. Based on the theoretical analysis and the concept of orthogonal basis expansion, we develop a time-domain phase noise estimation and suppression method for polarization-division-multiplexed CO-OFDM/OQAM systems. As shown in numerical Montel Carlo simulations, the proposed method can improve the system robustness against phase noise effectively.
Autors: Xi Fang;Fan Zhang;
Appeared in: Journal of Lightwave Technology
Publication date: May 2017, volume: 35, issue:10, pages: 1837 - 1846
Publisher: IEEE
 
» Phase Retrieval for Wavelet Transforms
Abstract:
This paper describes a new algorithm that solves a particular phase retrieval problem, with important applications in audio processing: the reconstruction of a function from its scalogram, that is, from the modulus of its wavelet transform. It is a multiscale iterative algorithm that reconstructs the signal from low-to-high frequencies. It relies on a new reformulation of the phase retrieval problem that involves the holomorphic extension of the wavelet transform. This reformulation allows to propagate phase information from low-to-high frequencies. Numerical results, on audio and non-audio signals, show that reconstruction is precise and stable to noise. The complexity of the algorithm is linear in the size of the signal, up to logarithmic factors. It can thus be applied to large signals.
Autors: Irène Waldspurger;
Appeared in: IEEE Transactions on Information Theory
Publication date: May 2017, volume: 63, issue:5, pages: 2993 - 3009
Publisher: IEEE
 
» Phenomenological Transparency
Abstract:
Translucent objects such as fog, clouds, smoke, glass, ice, and liquids are pervasive in cinematic environments because they frame scenes in depth and create visually-compelling shots. Unfortunately, they are hard to render in real-time and have thus previously been rendered poorly compared to opaque surfaces. This paper introduces the first model for a real-time rasterization algorithm that can simultaneously approximate the following transparency phenomena: wavelength-varying (“colored”) transmission, translucent colored shadows, caustics, volumetric light and shadowing, partial coverage, diffusion, and refraction. All render efficiently with order-independent draw calls and low bandwidth. We include source code.
Autors: Morgan McGuire;Michael Mara;
Appeared in: IEEE Transactions on Visualization and Computer Graphics
Publication date: May 2017, volume: 23, issue:5, pages: 1465 - 1478
Publisher: IEEE
 
» Photonic Generation of Linear-Frequency-Modulated Waveforms With Improved Time-Bandwidth Product Based on Polarization Modulation
Abstract:
Polarization modulation of two phase-correlated, orthogonally polarized wavelengths by a parabolic waveform is a promising way to generate linear-frequency-modulated (LFM) signals, but the time-bandwidth product (TBWP) of the generated LFM signal is intrinsically limited by the achievable modulation index of the polarization modulator (PolM). In this paper, an approach to increase the TBWP of the LFM signal generated by polarization modulation is proposed and comprehensively studied by splitting the electrical parabolic waveforms into N pieces with identical amplitude. Applying the split parabolic signal to the PolM, the total equivalent phase shift would be boosted by N/2 times. As a result, the bandwidth as well as the TBWP of the generated LFM signal is increased by N/2 times. An experiment is carried out. As compared to the scheme using an unsplit parabolic signal, the TBWP is improved by more than 500 times. The relationships between the bandwidth, the time duration, and the TBWP of the generated signal with the parameters of the electrical waveform generator are discussed.
Autors: Yamei Zhang;Xingwei Ye;Qingshui Guo;Fangzheng Zhang;Shilong Pan;
Appeared in: Journal of Lightwave Technology
Publication date: May 2017, volume: 35, issue:10, pages: 1821 - 1829
Publisher: IEEE
 
» Physical Visualization of Geospatial Datasets
Abstract:
Geospatial datasets are too complex to easily visualize and understand on a computer screen. Combining digital fabrication with a discrete global grid system (DGGS) can produce physical models of the Earth for visualizing multiresolution geospatial datasets. This proposed approach includes a mechanism for attaching a set of 3D printed segments to produce a scalable model of the Earth. The authors have produced two models that support the attachment of different datasets both in 2D and 3D format.
Autors: Hessam Djavaherpour;Ali Mahdavi-Amiri;Faramarz F. Samavati;
Appeared in: IEEE Computer Graphics and Applications
Publication date: May 2017, volume: 38, issue:3, pages: 61 - 69
Publisher: IEEE
 
» Physically Based Model for Multispectral Image Simulation of Earth Observation Sensors
Abstract:
Physically based multispectral image simulation consists of sensor system modeling, bottom-of-atmosphere (BOA) image generation, and top-of-atmosphere (TOA) image calculation. TOA radiance images are usually generated using a lookup table (LUT) for computational efficiency, which is calculated by means of atmospheric radiative transfer codes with different combination of input variables, including viewing zenith, solar zenith, and relative azimuth angles; visibility; columnar water vapor; and ground elevation. In this paper, a new strategy is proposed for TOA radiance image simulation, where transmitted surface radiance and atmospheric radiance at the TOA are calculated, respectively, to improve accuracy as well as efficiency. The transmitted surface radiance image is obtained from pixel-by-pixel calculation of BOA radiance and path transmittance. In calculating the atmospheric radiance of TOA, two LUTs are built for the emitted and the scattered radiance from each atmospheric layer, respectively. The effects of visibility and columnar water vapor on the atmospheric radiance are characterized by means of an equivalent path transmittance, which is related to the scene geometry as well as the thickness of atmospheric layer. In this way, when a new scene is simulated, except for three variables, i.e., viewing and solar zenith angles and atmospheric layer number, other parameters are set as constants in building the LUTs, enabling more combinations of input variables without adding excessive computational burden. Multispectral images in different bands with moderate spatial resolution are simulated and compared with the moderate-resolution imaging spectroradiometer (MODIS) images to demonstrate the accuracy and the usefulness of the proposed strategy.
Autors: Xiaoyu He;Xiaojian Xu;
Appeared in: IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing
Publication date: May 2017, volume: 10, issue:5, pages: 1897 - 1908
Publisher: IEEE
 
» PID controller based on a self-adaptive neural network to ensure qos bandwidth requirements in passive optical networks
Abstract:
In this paper, a proportional-integral-derivative (PID) controller integrated with a neural network (NN) is proposed to ensure quality of service (QoS) bandwidth requirements in passive optical networks (PONs). To the best of our knowledge, this is the first time an approach that implements aNNto tune a PID to dealwithQoS in PONs is used. In contrast to other tuning techniques such as Ziegler– Nichols or genetic algorithms (GA), our proposal allows a real-time adjustment of the tuning parameters according to the network conditions. Thus, the new algorithm provides an online control of the tuning process unlike the ZN and GA techniques, whose tuning parameters are calculated offline. The algorithm, called neural network service level PID (NNSPID), guarantees minimum bandwidth levels to users depending on their service level agreement, and it is compared with a tuning technique based on genetic algorithms (GASPID). The simulation study demonstrates that NN-SPID continuously adapts the tuning parameters, achieving lower fluctuations than GA-SPID in the allocation process. As a consequence, it provides a more stable response than GA-SPID since it needs to launch the GA to obtain new tuning values. Furthermore, NN-SPID guarantees the minimum bandwidth levels faster than GA-SPID. Finally, NN-SPID is more robust than GA-SPID under real-time changes of the guaranteed bandwidth levels, as GA-SPID shows high fluctuations in the allocated bandwidth, especially just after any change is made.
Autors: N. Merayo;D. Juárez;Juan C. Aguado;I. De Miguel;R. J. Durán;P. Fernández;R. M. Lorenzo;E. J. Abril;
Appeared in: IEEE/OSA Journal of Optical Communications and Networking
Publication date: May 2017, volume: 9, issue:5, pages: 433 - 445
Publisher: IEEE
 
» Planar Wideband Differential-Mode Bandpass Filter With Common-Mode Noise Absorption
Abstract:
In this letter, a planar differential-mode (DM) four-port circuit is proposed to design a balanced-to-balanced bandpass filter (BPF) with common-mode noise absorption add-on feature. By using the matrix transformation between the mixed and the single-ended scattering parameters, even- (odd-) mode equivalent circuit and the closed-form solutions of the proposed circuit structure are obtained based on the constraint rules. Finally, a microstrip DM BPF is designed and fabricated. The measured (simulated) results show that the relative bandwidth is 55.5% (57.5%) under the conditions of dB and , , and dB. Good agreements between the simulated and measured results verify the correctness of the design theory.
Autors: Weiwei Zhang;Yongle Wu;Yuanan Liu;Cuiping Yu;Abul Hasan;Fadhel M. Ghannouchi;
Appeared in: IEEE Microwave and Wireless Components Letters
Publication date: May 2017, volume: 27, issue:5, pages: 458 - 460
Publisher: IEEE
 
» Planar-Nanostrip-Channel InAlN/GaN HEMTs on Si With Improved ${g}_{{m}}$ and ${f}_{textsf {T}}$ Linearity
Abstract:
In this letter, we report an InAlN/GaN high electron mobility transistor (HEMT) with a planar nanostrip channel design to improve its transconductance and cut-off frequency linearity. The planar nanostrips were formed by partial arsenic ion implantation isolation in the channel under the gate. Devices with a gate length () of 80 nm and a source-to-drain distance () of 1 were fabricated. A conventional device and a device with a fin-like nanowire channel were also fabricated together for comparison. It was observed that the nanostrip and nanowire channel structures can both suppress the access resistance increase at the high output current level, and thereby improve the device’s and linearity. Compared to the one using etching to form a fin-like nanostrip channel, the GaN HEMT with a planar nanostrip channel has demonstrated reduced parasitic capacitance and improved RF performance.
Autors: Weichuan Xing;Zhihong Liu;Haodong Qiu;Geok Ing Ng;Tomás Palacios;
Appeared in: IEEE Electron Device Letters
Publication date: May 2017, volume: 38, issue:5, pages: 619 - 622
Publisher: IEEE
 

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